For over 20 years, the parallel bus interface has been the most common communication protocol for most digital storage systems. But as the need for bandwidth and system flexibility has grown, the shortcomings of the two most common parallel interface technologies, SCSI and ATA, have become apparent. The lack of compatibility between SCSI and ATA parallel interfaces—different connectors, cables, and instruction sets used—increases the cost of system maintenance, research and development, training, and qualification of new products.

To date, parallel technologies are still satisfying users of modern enterprise systems in terms of performance, but the growing need for higher speeds, higher data transmission integrity, reduced physical size, and wider standardization is calling into question the ability of a parallel interface without unnecessary costs to keep up with rapidly growing CPU performance and hard drive speeds. In addition, in an austerity environment, it is becoming increasingly difficult for enterprises to find funds to develop and maintain heterogeneous back panel connectors for server chassis and external disk arrays, verify heterogeneous interface compatibility, and inventory heterogeneous I/O connections.

The use of parallel interfaces also comes with a number of other problems. Parallel data transmission over a wide stub cable is subject to crosstalk, which can create additional noise and signal errors - to avoid this trap, you have to reduce the signal speed or limit the length of the cable, or both. Termination of parallel signals is also associated with certain difficulties - you have to terminate each line separately, usually the last drive performs this operation in order to prevent signal reflection at the end of the cable. Finally, the large cables and connectors used in parallel interfaces make these technologies unsuitable for new compact computing systems.

Introducing SAS and SATA

Serial technologies such as Serial ATA (SATA) and Serial Attached SCSI (SAS) overcome the architectural limitations of traditional parallel interfaces. These new technologies got their name from the method of signal transmission, when all information is transmitted sequentially (English serial), in a single stream, in contrast to multiple streams that are used in parallel technologies. The main advantage of the serial interface is that when data is transferred in a single stream, it moves much faster than when using a parallel interface.

Serial technologies combine many bits of data into packets and then transfer them over a cable at speeds up to 30 times faster than parallel interfaces.

SATA expands on the capabilities of traditional ATA technology by enabling data transfer between disk drives at rates of 1.5 GB per second or more. Due to its low cost per gigabyte of disk capacity, SATA will continue to be the dominant disk interface in desktop PCs, entry-level servers, and network storage systems, where cost is one of the main considerations.

SAS, the successor to parallel SCSI, builds on the proven high functionality of its predecessor and promises to greatly expand the capabilities of today's enterprise storage systems. SAS has a number of advantages that are not available with traditional storage solutions. In particular, SAS allows up to 16,256 devices to be connected to a single port and provides a reliable point-to-point serial connection at speeds up to 3 Gb / s.

In addition, the smaller SAS connector provides full two-port connectivity for both 3.5" and 2.5" hard drives (previously only available on 3.5" Fiber Channel hard drives). This is very useful feature where you need to fit a lot of redundant drives into a compact system, such as a low profile blade server.

SAS improves drive addressing and connectivity with hardware expanders that allow a large number of drives to be connected to one or more host controllers. Each expander provides connections for up to 128 physical devices, which can be other host controllers, other SAS expanders or disk drives. This scheme scales well and allows you to create enterprise-scale topologies that easily support multi-node clustering for automatic system recovery in case of failure and for load balancing.

One of the biggest benefits of the new serial technology is that the SAS interface will also be compatible with more cost-effective SATA drives, allowing system designers to use both types of drives in the same system without the additional expense of supporting two different interfaces. Thus, the SAS interface, representing the next generation of SCSI technology, overcomes the existing limitations of parallel technologies in terms of performance, scalability, and data availability.

Multiple levels of compatibility

Physical Compatibility

The SAS connector is universal and form factor compatible with SATA. This allows both SAS and SATA drives to be directly connected to the SAS system and thus use the system either for life. important applications that require high performance and fast data access, or for more cost-effective applications with a lower cost per gigabyte.

The SATA command set is a subset of the SAS command set, which provides compatibility between SATA devices and SAS controllers. However, SAS drives cannot work with a SATA controller, so they are provided with special keys on the connectors to eliminate the possibility of incorrect connection.

In addition, the similar physical parameters of the SAS and SATA interfaces allow for a new universal SAS backplane that supports both SAS and SATA drives. As a result, there is no need to use two different backplates for SCSI and ATA drives. This interoperability benefits both backplate manufacturers and end users by reducing hardware and engineering costs.

Protocol level compatibility

SAS technology includes three types of protocols, each of which is used to transfer different types of data over a serial interface, depending on which device is being accessed. The first is the serial SCSI protocol (Serial SCSI Protocol SSP), which transmits SCSI commands, the second is the SCSI Management Protocol (SMP), which transmits control information to the expanders. The third, SATA Tunneled Protocol STP, establishes a connection that allows the transmission of SATA commands. Using these three protocols, the SAS interface is fully compatible with existing SCSI applications, management software, and SATA devices.

This multi-protocol architecture, combined with the physical compatibility of SAS and SATA connectors, makes SAS technology the universal link between SAS and SATA devices.

Compatibility Benefits

SAS and SATA compatibility gives whole line benefits to system designers, assemblers and end users.

System designers can use the same backplates, connectors, and cable connections due to SAS and SATA compatibility. Upgrading the system from SATA to SAS is actually a replacement of disk drives. In contrast, for users of traditional parallel interfaces, moving from ATA to SCSI means changing back panels, connectors, cables, and drives. Other cost-effective interoperability benefits of serial technologies include simplified certification and asset management.

VAR resellers and system builders can quickly and easily reconfigure custom systems by simply installing the appropriate disk drive into the system. There is no need to work with incompatible technologies and use special connectors and different cable connections. What's more, the added flexibility in choosing the best price/performance ratio will allow VAR resellers and system builders to better differentiate their products.

For end users, SATA and SAS compatibility means a new level of flexibility when it comes to choosing the best price/performance ratio. SATA drives are the best solution for low-cost servers and storage systems, while SAS drives provide maximum performance, reliability and management software compatibility. Upgradable from SATA drives to SAS drives without having to purchase new system greatly simplifies the purchasing decision process, protects system investment and reduces total cost of ownership.

Joint development of SAS and SATA protocols

On January 20, 2003, the SCSI Trade Association (STA) and Working group Serial ATA (SATA) II Working Group announced a collaboration to ensure that SAS technology is compatible with SATA disk drives at the system level.

The collaboration of the two organizations, as well as the joint efforts of storage vendors and standards committees, is aimed at developing even more precise compatibility guidelines that will help system designers, IT professionals and end users to fine-tune their systems even more to achieve optimal performance. and reliability and lower total cost of ownership.

The SATA 1.0 specification was approved in 2001, and SATA products from various manufacturers are on the market today. The SAS 1.0 specification was approved in early 2003, and the first products should hit the market in the first half of 2004.

With the advent of a sufficiently large number of Serial Attached SCSI (SAS) peripherals, we can state the beginning of the transition of the corporate environment to the rails of the new technology. But SAS is not only a recognized successor to UltraSCSI technology, but also opens up new areas of use, raising the scalability of systems downright to unthinkable heights. We decided to demonstrate the potential of SAS by taking a closer look at the technology, host adapters, hard drives, and storage systems.

SAS is not a completely new technology: it takes the best of both worlds. The first part of SAS is about serial communication, which requires less physical wires and pins. The transition from parallel to serial transmission made it possible to get rid of the bus. Although current SAS specifications throughput specified at 300 MB/s per port, which is less than 320 MB/s for UltraSCSI, replacing the shared bus with a point-to-point connection is a significant benefit. The second part of SAS is the SCSI protocol, which remains powerful and popular.

SAS can also use a large set types of RAID. Giants such as Adaptec or LSI Logic offer an advanced set of features for expansion, migration, nesting, and other features in their products, including distributed RAID arrays across multiple controllers and drives.

Finally, most of the actions mentioned today are already performed "on the fly". Here we should note excellent products AMCC/3Ware , Areca and Broadcom/Raidcore, which allowed the transfer of enterprise-class features to SATA spaces.

Compared to SATA, the traditional SCSI implementation is losing ground on all fronts except in high-end enterprise solutions. SATA offers suitable hard drives, has a good price and a wide range of decisions. And let's not forget another "smart" feature of SAS: it easily gets along with existing SATA infrastructures, since SAS host adapters easily work with SATA drives. But the SAS drive cannot be connected to the SATA adapter.

Source: Adaptec.

First, it seems to us, we should turn to the history of SAS. The SCSI standard stands for "small computer system interface". computer systems") has always been regarded as a professional bus for connecting drives and some other devices to computers. Hard drives for servers and workstations still use SCSI technology. Unlike the mass ATA standard, which allows you to connect only two drives to one port, SCSI allows you to connect up to 15 devices on one bus and offers a powerful command protocol Devices must have a unique SCSI ID, which can be assigned either manually or via the SCAM (SCSI Configuration Automatically) protocol Since the device IDs for buses of two or more SCSI adapters can be not unique, LUNs (Logical Unit Numbers) have been added to identify devices in complex SCSI environments.

SCSI hardware is more flexible and reliable than ATA (this standard is also called IDE, Integrated Drive Electronics). Devices can be connected both inside the computer and outside, and the cable length can be up to 12 m, if it is properly terminated (in order to avoid signal reflections). As SCSI has evolved, numerous standards have emerged that specify different bus widths, clock speeds, connectors, and signal voltages (Fast, Wide, Ultra, Ultra Wide, Ultra2, Ultra2 Wide, Ultra3, Ultra320 SCSI). Luckily, they all use the same set of commands.

Any SCSI communication is established between the initiator (host adapter) sending commands and the target drive responding to them. Immediately after receiving a set of commands, the target drive sends a so-called sense code (status: busy, error or free), by which the initiator will know whether he will receive the desired response or not.

The SCSI protocol specifies almost 60 different commands. They are divided into four categories: non-data, bi-directional, read data, and write data.

The limitations of SCSI start to show up when you add drives to the bus. Today it is hardly possible to find a hard drive that can fully load the 320 MB / s throughput of Ultra320 SCSI. But five or more drives on the same bus is another matter entirely. An option would be to add a second host adapter for load balancing, but this comes at a cost. Cables are also a problem: twisted 80-wire cables are very expensive. If you also want to get a "hot swap" of drives, that is, an easy replacement of a failed drive, then special equipment (backplane) is required.

Of course, it's best to place the drives in separate fixtures or modules, which are usually hot swappable along with other nice control features. As a result, there are more professional SCSI solutions on the market. But they all cost a lot, which is why the SATA standard has developed so rapidly in recent years. And although SATA will never meet the needs of high-end enterprise systems, this standard perfectly complements SAS in creating new scalable solutions for next-generation network environments.

SAS does not use a common bus for multiple devices. Source: Adaptec.

SATA

On the left is the SATA connector for data transfer. On the right is the power connector. There are enough pins to supply 3.3V, 5V, and 12V voltages to each SATA drive.

The SATA standard has been on the market for several years, and today it has reached its second generation. SATA I featured 1.5 Gb/s throughput with two serial connections using low-voltage differential signaling. The physical layer uses 8/10 bit encoding (10 actual bits for 8 bits of data), which accounts for the maximum interface throughput of 150 MB/s. After the transition of SATA to a speed of 300 MB / s, many began to call the new standard SATA II, although during standardization SATA-IO(International Organization) planned to add more features first and then call it SATA II. Hence the latest specification is called SATA 2.5, it includes SATA extensions such as Native Command Queuing(NCQ) and eSATA (external SATA), port multipliers (up to four drives per port), etc. But additional functions SATA is optional for both the controller and the hard drive itself.

Let's hope that in 2007 SATA III at 600 MB / s will still be released.

Where parallel ATA (UltraATA) cables were limited to 46cm, SATA cables can be up to 1m long, and for eSATA twice that. Instead of 40 or 80 wires, serial transmission requires only a few pins. Therefore, SATA cables are very narrow, easy to route inside a computer case, and don't obstruct airflow as much. A single device relies on a SATA port, making it a point-to-point interface.

SATA connectors for data and power provide separate plugs.

SAS

The signaling protocol here is the same as that of SATA. Source: Adaptec.

A nice feature of Serial Attached SCSI is that the technology supports both SCSI and SATA, as a result of which SAS or SATA drives (or both standards) can be connected to SAS controllers. However, SAS drives cannot work with SATA controllers due to the use of the Serial SCSI Protocol (SSP). Like SATA, SAS follows the point-to-point connection principle for drives (300 MB/s today), and thanks to SAS expanders (or expanders, expanders), more drives can be connected than are available SAS ports. SAS hard drives support two ports, each with its own unique SAS ID, so you can use two physical connections to provide redundancy - connect the drive to two different hosts. Thanks to STP (SATA Tunneling Protocol), SAS controllers can communicate with SATA drives connected to the expander.

Source: Adaptec.

Source: Adaptec.

Source: Adaptec.

Of course, the only physical connection of the SAS expander to the host controller can be considered a "bottleneck", so wide SAS ports are provided in the standard. A wide port groups multiple SAS connections into a single link between any two SAS devices (usually between a host controller and an extender/expander). The number of connections within the connection can be increased, it all depends on the requirements imposed. But redundant connections are not supported, nor are any loops or rings allowed.

Source: Adaptec.

Future implementations of SAS will add 600 and 1200 MB/s bandwidth per port. Of course, the performance of hard drives will not increase in the same proportion, but it will be more convenient to use expanders on a small number of ports.

Devices called "Fan Out" and "Edge" are expanders. But only the main Fan Out expander can work with the SAS domain (see 4x connection in the center of the diagram). Each Edge expander is allowed up to 128 physical connections, and you can use wide ports and / or connect other expanders / drives. The topology can be quite complex, but at the same time flexible and powerful. Source: Adaptec.

Source: Adaptec.

The backplane is the basic building block of any storage system that needs to be hot pluggable. That's why SAS expanders often mean powerful snap-ins (both in a single case and not). Typically, a single link is used to connect a simple snap-in to a host adapter. Expanders with built-in snap-ins, of course, rely on multi-channel connections.

Three types of cables and connectors have been developed for SAS. SFF-8484 is a multicore internal cable that connects the host adapter to the equipment. In principle, the same can be achieved by branching this cable at one end into several separate SAS connectors (see illustration below). SFF-8482 is a connector through which the drive is connected to a single SAS interface. Finally, the SFF-8470 is an external multicore cable, up to six meters long.

Source: Adaptec.

SFF-8470 cable for external multilink SAS connections.

Multicore cable SFF-8484. Four SAS channels/ports pass through one connector.

SFF-8484 cable that allows you to connect four SATA drives.

SAS as part of SAN solutions

Why do we need all this information? Most users will not come close to the SAS topology we discussed above. But SAS is more than a next-generation interface for professional hard drives, although it is ideal for building simple to complex RAID arrays based on one or more RAID controllers. SAS is capable of more. This is a point-to-point serial interface that scales easily as you add more links between any two SAS devices. SAS drives come with two ports, so you can connect one port through an expander to a host system and then create a backup path to another host system (or another expander).

Communication between SAS adapters and expanders (as well as between two expanders) can be as wide as there are available SAS ports. Expanders are usually rackmount systems that can accommodate a large number of drives, and the possible connection of SAS to a higher device in the hierarchy (for example, a host controller) is limited only by the capabilities of the expander.

With a rich and functional infrastructure, SAS allows you to create complex storage topologies, rather than dedicated hard drives or separate network storage. In this case, "complicated" should not mean that it is difficult to work with such a topology. SAS configurations consist of simple disk rigs or use expanders. Any SAS link can be scaled up or down depending on bandwidth requirements. You can use both powerful SAS hard drives and high-capacity SATA models. Together with powerful RAID controllers, you can easily set up, expand or reconfigure data arrays - both in terms of the RAID level and the hardware side.

All of this becomes even more important when you consider how fast corporate storage is growing. Today everyone is talking about SAN - storage area network. It implies a decentralized organization of a data storage subsystem with traditional servers using physically remote storages. By existing networks gigabit Ethernet or Fiber Channel, a slightly modified SCSI protocol is launched, encapsulated in Ethernet packets (iSCSI - Internet SCSI). A system that runs from a single hard drive to complex nested RAID arrays becomes a so-called target (target) and is tied to an initiator (host system, initiator), which treats the target as if it were just a physical element.

iSCSI, of course, allows you to create a strategy for the development of storage, data organization or access control. We get another level of flexibility by removing storage directly attached to servers, allowing any storage subsystem to become an iSCSI target. Moving to remote storage makes the system independent of storage servers (a dangerous point of failure) and improves the manageability of the hardware. From a programmatic point of view, the storage is still "inside" the server. The iSCSI target and initiator can be nearby, on different floors, in different rooms or buildings - it all depends on the quality and speed of the IP connection between them. From this point of view, it is important to note that the SAN is not well suited to the requirements of online applications such as databases.

2.5" SAS hard drives

2.5" hard drives for the professional sector are still perceived as a novelty. We have been reviewing the first such drive from Seagate for quite some time - 2.5" Ultra320 Savvio who left a good impression. All 2.5" SCSI drives use a 10,000 RPM spindle speed, but they fall short of the performance levels of 3.5" hard drives with the same spindle speed. The fact is that the outer tracks of 3.5 "models rotate at a higher linear speed, which provides a higher data transfer rate.

The advantage of small hard drives lies not in capacity: today the maximum for them is still 73 GB, while in 3.5 "enterprise-class hard drives we already get 300 GB. In many areas, the ratio of performance to physical volume occupied is very important or power efficiency. The more hard drives you use, the more performance you reap - paired with the appropriate infrastructure, of course. At the same time, 2.5" hard drives consume almost half as much energy as 3.5" competitors. If we consider the ratio performance per watt (I/O operations per watt), the 2.5" form factor gives very good results.

If you're looking for capacity first and foremost, 3.5" 10,000 rpm drives are unlikely to be the best choice. The fact is that 3.5" SATA hard drives provide 66% more capacity (500 instead of 300 GB per hard drive), leaving the performance level acceptable. Many hard drive manufacturers offer SATA models for 24/7 operation, and the price of drives Reliability problems can be solved by purchasing spare (spare) drives for immediate replacement in the array.

The MAY line represents Fujitsu's current generation of 2.5" drives for the professional sector. The rotation speed is 10,025 rpm, and the capacities are 36.7 and 73.5 GB. All drives come with 8 MB cache and give an average read seek time 4.0 ms and 4.5 ms writes As we already mentioned, a nice feature of 2.5" hard drives is reduced power consumption. Usually one 2.5" hard drive saves at least 60% of energy compared to a 3.5" drive.

3.5" SAS hard drives

The MAX is Fujitsu's current line of high performance 15,000 rpm hard drives. So the name fits perfectly. Unlike 2.5" drives, here we get a whopping 16MB of cache and a short average seek time of 3.3ms for reads and 3.8ms for writes. Fujitsu offers models in 36.7GB, 73.4GB, and 146 GB (with one, two and four plates).

Fluid dynamic bearings have made their way to enterprise-class hard drives, so the new models are significantly quieter than the previous ones at 15,000 rpm. Of course, such hard drives should be properly cooled, and the equipment provides this too.

Hitachi Global Storage Technologies also offers its own line of high performance solutions. The UltraStar 15K147 runs at 15,000 rpm and has a 16 MB cache, just like the Fujitsu drives, but the platter configuration is different. The 36.7 GB model uses two platters instead of one, while the 73.4 GB model uses three platters instead of two. This indicates a lower data density, but such a design, in fact, allows you to not use the inner, slowest areas of the plates. As a result, the heads have to move less, which gives a better average access time.

Hitachi also offers 36.7GB, 73.4GB, and 147GB models with a claimed seek (read) time of 3.7ms.

Although Maxtor has already become part of Seagate, the company's product lines are still preserved. The manufacturer offers 36, 73 and 147 GB models, all of which feature a 15,000 rpm spindle speed and 16 MB cache. The company claims an average seek time of 3.4ms for reads and 3.8ms for writes.

The Cheetah has long been associated with high performance hard drives. Seagate was able to instill a similar association with the release of the Barracuda in the desktop segment, offering the first 7200 RPM desktop drive in 2000.

Available in 36.7 GB, 73.4 GB and 146.8 GB models. All of them are distinguished by a spindle speed of 15,000 rpm and an 8 MB cache. The average seek time for reading is 3.5 ms and for writing 4.0 ms.

Host adapters

Unlike SATA controllers, SAS components can only be found on server-grade motherboards or as expansion cards for PCI-X or PCI Express. If we take it a step further and look at RAID controllers (Redundant Array of Inexpensive Drives), they are sold, for the most part, as individual cards due to their complexity. RAID cards contain not only the controller itself, but also a redundancy information calculation acceleration chip (XOR engine), as well as cache memory. A small amount of memory is sometimes soldered onto the card (most often 128 MB), but some cards allow you to expand the amount using a DIMM or SO-DIMM.

When choosing a host adapter or RAID controller, you should clearly define what you need. The range of new devices is growing just before our eyes. Simple multiport host adapters will cost relatively little, while powerful RAID cards will cost a lot. Think about where you will place the drives: for external storage requires at least one external connector. Rack servers typically require low profile cards.

If you need RAID, then decide whether you will use hardware acceleration. Some RAID cards take up resources CPU for XOR calculations for RAID 5 or 6 arrays; others use their own XOR hardware engine. RAID acceleration is recommended for environments where the server does more than store data, such as databases or web servers.

All of the host adapter cards that we cited in our article support 300 MB/s per SAS port and allow for very flexible implementation of the storage infrastructure. Today, few people will be surprised by external ports, and take into account the support for both SAS and SATA hard drives. All three cards use the PCI-X interface, but versions under PCI Express are already in development.

In our article, we paid attention to cards with eight ports, but the number of connected hard drives is not limited to this. With the help of a SAS expander (external), you can connect any storage. As long as a 4-lane connection is sufficient, you can increase the number of hard drives up to 122. Due to the performance cost of calculating the RAID 5 or RAID 6 parity information, typical external RAID storages will not be able to load the quad-lane bandwidth enough, even if a large number of drives are used.

48300 is a SAS host adapter designed for the PCI-X bus. The server market today continues to be dominated by PCI-X, although more and more motherboards are equipped with PCI Express interfaces.

The Adaptec SAS 48300 uses a PCI-X interface at 133 MHz, giving a throughput of 1.06 GB/s. Fast enough if PCI bus-X is not loaded by other devices. If you include a lower speed device in the bus, then all other PCI-X cards reduce their speed to the same. For this purpose, several PCI-X controllers are sometimes installed on the board.

Adaptec is positioning the SAS 4800 for midrange and low end servers and workstations. The suggested retail price is $360, which is quite reasonable. The Adaptec HostRAID feature is supported, allowing you to upgrade to the simplest RAID arrays. In this case, these are RAID levels 0, 1, and 10. The card supports an external four-channel SFF8470 connection, as well as an internal SFF8484 connector paired with a cable for four SAS devices, that is, we get eight ports in total.

The card fits into a 2U rack server when a low-profile slot cover is installed. The package also includes a CD with a driver, a quick installation guide, and an internal SAS cable through which up to four system drives can be connected to the card.

SAS player LSI Logic sent us a SAS3442X PCI-X host adapter, a direct competitor to the Adaptec SAS 48300. It comes with eight SAS ports that are split between two quad-lane interfaces. The "heart" of the card is the LSI SAS1068 chip. One of the interfaces is for internal devices, the second one is for external DAS (Direct Attached Storage). The board uses the PCI-X 133 bus interface.

As usual, 300 MB/s interface is supported for SATA and SAS drives. There are 16 LEDs on the controller board. Eight of them are simple activity LEDs, and eight more are designed to report a system malfunction.

The LSI SAS3442X is a low profile card, so it fits easily into any 2U rack server.

Note driver support for Linux, Netware 5.1 and 6, Windows 2000 and Server 2003 (x64), Windows XP (x64) and Solaris up to 2.10. Unlike Adaptec, LSI chose not to add support for any RAID modes.

RAID adapters

SAS RAID4800SAS is Adaptec's solution for more complex SAS environments, it can be used for application servers, servers streaming etc. Before us, again, is an eight-port card, with one external four-lane SAS connection and two internal four-lane interfaces. But if an external connection is used, then only one four-channel interface remains from the internal ones.

The card is also designed for the PCI-X 133 bus, which provides sufficient bandwidth for even the most demanding RAID configurations.

As far as RAID modes are concerned, the SAS RAID 4800 easily outperforms its "younger brother": RAID levels 0, 1, 10, 5, 50 are supported by default if you have enough drives. Unlike the 48300, Adaptec has invested two SAS cables so you can connect eight hard drives to the controller right away. Unlike the 48300, the card requires a full size PCI slot-X.

If you decide to upgrade your card to Adaptec Advanced Data Protection Suite, you'll be able to upgrade to double redundant RAID modes (6, 60), as well as a range of enterprise-class features: striped mirror drive (RAID 1E), hot spacing (RAID 5EE), and copyback hot spare. The Adaptec Storage Manager utility has a browser-like interface and can be used to manage all Adaptec adapters.

Adaptec offers drivers for Windows Server 2003 (and x64), Windows 2000 Server, Windows XP (x64), Novell Netware, Red Hat Enterprise Linux 3 and 4, SuSe Linux Enterprise Server 8 and 9 and FreeBSD.

SAS snap-ins

The 335SAS is a four-drive SAS or SATA drive accessory, but must be connected to a SAS controller. Thanks to the 120mm fan, the drives will be well cooled. You will also need to connect two Molex power plugs to the equipment.

Adaptec has included an I2C cable that can be used to control the rig via an appropriate controller. But with SAS drives, this will no longer work. An additional LED cable is designed to signal the activity of the drives, but, again, only for SATA drives. The package also includes an internal SAS cable for four drives, so an external four-channel cable will be enough to connect the drives. If you want to use SATA drives, you will have to use SAS to SATA adapters.

The retail price of $369 is not cheap. But you will get a solid and reliable solution.

SAS storage

SANbloc S50 is a 12-drive enterprise-class solution. You will receive a 2U rackmount enclosure that connects to SAS controllers. This is one of the best examples of scalable SAS solutions. The 12 drives can be either SAS or SATA. Or represent a mixture of both types. The built-in expander can use one or two quad-lane SAS interfaces to connect the S50 to a host adapter or RAID controller. Since we have a clearly professional solution, it is equipped with two power supplies (with redundancy).

If you have already purchased an Adaptec SAS host adapter, you can easily connect it to the S50 and manage drives using the Adaptec Storage Manager. If you install 500 GB SATA hard drives, then we get 6 TB of storage. If we take 300 GB SAS drives, then the capacity will be 3.6 TB. Since the expander is connected to the host controller by two four-lane interfaces, we will get a throughput of 2.4 GB / s, which will be more than enough for an array of any type. If you install 12 drives in a RAID0 array, then the maximum throughput will be only 1.1 GB / s. In the middle of this year, Adaptec promises to release a slightly modified version with two independent SAS I/O blocks.

SANbloc S50 contains the function of automatic monitoring and automatic control of fan speed. Yes, the device is too loud, so we were relieved to return it from the lab after the tests were completed. A drive failure message is sent to the controller via SES-2 (SCSI Enclosure Services) or via the physical I2C interface.

Operating temperatures for actuators are 5-55°C, and for accessories - from 0 to 40°C.

At the start of our tests, we got a peak throughput of just 610 MB/s. By changing the cable between the S50 and the Adaptec host controller, we were still able to reach 760 MB / s. We used seven hard drives to load the system in RAID 0 mode. Increasing the number of hard drives did not lead to an increase in throughput.

Test configuration

System hardware
Processors	2x Intel Xeon (Nocona core) 3.6 GHz, FSB800, 1 MB L2 cache
Platform	Asus NCL-DS (Socket 604) Chipset Intel E7520, BIOS 1005
Memory	Corsair CM72DD512AR-400 (DDR2-400 ECC, reg.) 2x 512 MB, CL3-3-3-10
System hard drive	Western Digital Caviar WD1200JB 120 GB, 7200 rpm, 8 MB cache, UltraATA/100
Drive Controllers	Controller Intel 82801EB UltraATA/100 (ICH5) Promise SATA 300TX4 Driver 1.0.0.33 Adaptec AIC-7902B Ultra320 Driver 3.0 Adaptec 48300 8 port PCI-X SAS Driver 1.1.5472 Adaptec 4800 8 port PCI-X SAS Driver 5.1.0.8360 Firmware 5.1.0.8375 LSI Logic SAS3442X 8 port PCI-X SAS Driver 1.21.05 BIOS 6.01
Vaults	4-bay, hot-swappable indoor rig 2U, 12-HDD SAS/SATA JBOD
Net	Broadcom BCM5721 Gigabit Ethernet
video card	built-in ATi RageXL, 8 MB
Tests
performance measurement	c "t h2benchw 3.6
Measuring I/O performance	IOMeter 2003.05.10 Fileserver Benchmark webserver-benchmark database-benchmark Workstation Benchmark
System software and drivers
OS	Microsoft Windows Server 2003 Enterprise Edition Service Pack 1
Platform driver	Intel Chipset Installation Utility 7.0.0.1025
Graphics driver Workstation script. After examining several new SAS hard drives, three related controllers, and two snap-ins, it became clear that SAS is indeed a promising technology. If you refer to the SAS technical documentation, you will understand why. This is not only the successor to serial SCSI (fast, convenient and easy to use), but also an excellent level of scalability and infrastructure growth, in comparison with which Ultra320 SCSI solutions seem like a stone age. And the compatibility is just great. If you are planning to purchase professional equipment SATA for your server, then you should look at SAS. Any SAS controller or accessory is compatible with both SAS and SATA hard drives. Therefore, you can create both a high-performance SAS environment and a capacious SATA environment - or both. Convenient support for external storage is another important advantage of SAS. If the SATA storage uses either proprietary solutions or a single SATA/eSATA link, the SAS storage interface allows for increased bandwidth in groups of four SAS links. As a result, we get the opportunity to increase the bandwidth for the needs of applications, and not rest on 320 MB / s UltraSCSI or 300 MB / s SATA. Moreover, SAS expanders allow you to create a whole hierarchy of SAS devices, so that administrators have more freedom of action. The evolution of SAS devices will not end there. It seems to us that the UltraSCSI interface can be considered obsolete and slowly written off. It is unlikely that the industry will improve it, unless it continues to support existing implementations UltraSCSI. Still new hard drives, latest models storage and snap-ins, as well as an increase in interface speed to 600 MB / s, and then to 1200 MB / s - all this is intended for SAS. What should be a modern storage infrastructure? With the availability of SAS, the days of UltraSCSI are numbered. The sequential version is a logical step forward and does everything better than its predecessor. The question of choosing between UltraSCSI and SAS becomes obvious. Choosing between SAS or SATA is somewhat more difficult. But if you look into the future, then SAS components will still be better. Indeed, for maximum performance or in terms of scalability, there is no alternative to SAS today.

Today's file server or web server is indispensable without a RAID array. Only this mode of operation can provide the required throughput and speed of work with the storage system. Until recently, the only hard drives suitable for such work were SCSI drives with a spindle speed of 10-15 thousand revolutions per minute. These drives required a separate SCSI controller to operate. The data transfer rate over SCSI reached 320 Mb / s, however, the SCSI interface is a regular parallel interface, with all its shortcomings.

More recently, a new disk interface has appeared. It was called SAS (Serial Attached SCSI). Recreation centers in Chelyabinsk - Today, many companies already have controllers for this interface in their product line that support all levels of RAID arrays. In our mini-review, we'll take a look at two members of Adaptec's new SAS controller family. These are the 8 port model ASR-4800SAS and the 4+4 port model ASR-48300 12C.

Introduction to SAS

What kind of interface is this - SAS? Actually SAS is a hybrid of SATA and SCSI. The technology has absorbed the advantages of two interfaces. Let's start with the fact that SATA is a serial interface with two independent read and write channels, and each SATA device is connected to a separate channel. SCSI has a very efficient and reliable enterprise data transfer protocol, but the downside is the parallel interface and shared bus for multiple devices. Thus, SAS is free from the disadvantages of SCSI, has the advantages of SATA and provides speeds up to 300 Mb / s per channel. According to the diagram below, you can roughly imagine the connection scheme for SCSI and SAS.

The bidirectionality of the interface reduces latency to zero, since there is no channel switching to read / write.

An interesting and positive feature of Serial Attached SCSI is that this interface supports SAS and SATA drives, and both types of drives can be connected to the same controller at the same time. However, SAS drives cannot be connected to a SATA controller, since these drives, firstly, require special SCSI commands (Serial SCSI Protocol) to operate, and secondly, are physically incompatible with a SATA block. Each SAS drive connects to its own port, but it is still possible to connect more drives than the controller has ports. SAS-extenders (Expander) provide this opportunity.

The original difference between a SAS disk header and a SATA disk header is an additional data port, that is, each Serial Attached SCSI disk has two SAS ports with its own original ID, thus the technology provides redundancy, which improves reliability.

SAS cables are slightly different from SATA, and there is a special cable accessory included with the SAS controller. Just like SCSI, hard drives of the new standard can be connected not only inside the server case, but also outside, for which special cables and accessories are provided. To connect "hot-swappable" disks, special boards are used - backplane, which have all the necessary connectors and ports for connecting disks and controllers.

As a rule, the backplane board is located in a special case with disk sled mounting, such a case contains a RAID array and provides its cooling. In the event of failure of one or several disks, it is possible to quickly replace a failed HDD, and replacing a failed drive does not stop the operation of the array - just change the disk and the array is fully functional again.

Adaptec SAS adapters

Adaptec has presented two rather interesting models of RAID controllers for your consideration. The first model is a representative of the budget class of devices for building RAID in low-cost entry-level servers - this is the eight-port model ASR-48300 12C. The second model is much more advanced and designed for more serious tasks, it has eight SAS channels on board - this is the ASR-4800SAS. But let's take a closer look at each of them. Let's start with a simpler and cheaper model.

Adaptec ASR-48300 12C

The ASR-48300 12C controller is designed to build small RAID arrays of levels 0, 1 and 10. Thus, the main types of disk arrays can be built using this controller. This model is supplied in an ordinary cardboard box, which is decorated in blue and black colors, on the front side of the package there is a stylized image of a controller flying from a computer, which should evoke thoughts about the high speed of a computer with this device inside.

The scope of delivery is minimal, but includes everything you need to get started with the controller. The kit contains the following.

Controller ASR-48300 12C
. Low profile brace

. Storage Manager CD
. Brief manual
. Connecting cable with connectors SFF8484 to 4xSFF8482 and power supply 0.5 m.

The controller is designed for the PCI-X 133 MHz bus, which is very widespread in server platforms. The adapter provides eight SAS ports, however, only four ports are implemented as an SFF8484 connector, to which drives are connected inside the case, and the remaining four channels are brought out in the form of an SFF8470 connector, so some of the drives must be connected from the outside - this can be an external box with four drives inside.

When using the expander, the controller has the ability to work with 128 disks in the array. In addition, the controller is able to work in a 64-bit environment and supports the corresponding commands. The card can be installed in a 2U low profile server with the included low profile blanking plate. The general characteristics of the board are as follows.

Advantages

Cost-effective Serial Attached SCSI controller with Adaptec HostRAID™ technology for high performance critical data storage.

Client needs

Ideal for supporting entry-level, mid-range, and workgroup server applications that require high-performance storage and robust security, such as applications Reserve copy, web content, email, databases and data sharing.

System Environment - Department and Workgroup Servers

System bus interface type - PCI-X 64 bit/133 MHz, PCI 33/66

External connections - One x 4 Infiniband/Serial Attached SCSI (SFF8470)

Internal connections - One 32 pin x 4 Serial Attached SCSI (SFF8484)

System Requirements - Server Type IA-32, AMD-32, EM64T and AMD-64

32/64-bit PCI 2.2 or 32/64-bit PCI-X 133 slot

Warranty - 3 years

RAID levels - Adaptec HostRAID 0, 1, and 10

Key features of RAID

• Support for boot arrays
• Automatic recovery
• Management with Adaptec Storage Manager software
• Background initialization

Board dimensions - 6.35cm x 17.78cm (including external connector)

Operating temperature - 0° to 50° C

Power dissipation - 4 W

Mean Time Before Failure (MTBF - time between failures) - 1692573 hours at 40 ºC.

Adaptec ASR-4800SAS

Adapter number 4800 is more functionally advanced. This model is positioned for faster servers and workstations. It supports almost any RAID arrays - arrays that are available on the younger model, and you can also configure arrays of RAID 5, 50, JBOD and Adaptec Advanced Data Protection Suite with RAID 1E, 5EE, 6, 60, Copyback Hot Spare with the Snapshot Backup option for tower servers and high-density rack servers.

The model comes in a package similar to the junior model with the design in the same "aviation" style.

The kit contains almost the same as the junior card.

Controller ASR-4800SAS
. Full size brace
. Driver disk and complete guide
. Storage Manager CD
. Brief manual
. Two cables with connectors SFF8484 to 4xSFF8482 and power supply 1 m each.

The controller supports the 133MHz PCI-X bus, but there is also a 4805 model that is functionally similar but uses the PCI-E x8 bus. The adapter provides the same eight SAS ports, however, all eight ports are implemented as internal ones, respectively, the board has two SFF8484 connectors (for two bundled cables), however, there is also an external connector of the SFF8470 type for four channels, when connected to which one of the internal connectors turns off.

In the same way as in the younger device, the number of disks is expandable up to 128 using expanders. But the main difference between the ASR-4800SAS model and the ASR-48300 12C is the presence of 128 MB DDR2 ECC memory used as a cache on the first one, which speeds up work with the disk array and optimizes work with small files. An optional battery module is available to save data in the cache when the power is turned off. The general characteristics of the board are as follows.

Benefits - High performance storage and data protection connectivity for servers and workstations

Customer Needs — Ideal for supporting server and workgroup applications that require consistently high levels of read/write performance, such as video streaming, web content, video-on-demand, fixed content, and reference data storage.

• System Environment - Department and Workgroup Servers and Workstations
• System Bus Interface Type - PCI-X 64-bit/133 MHz host interface
• External connections - SAS connector one x4
• Internal connections - SAS connectors two x4
• Data Transfer Rate - Up to 3 GB/s per port
• System Requirements - Intel or AMD architecture with free 64-bit 3.3v PCI-X slot
• Supports EM64T and AMD64 architectures
• Warranty - 3 years
• Standard RAID Levels - RAID 0, 1, 10, 5, 50
• Standard RAID Features - Hot Spare, RAID Level Migration, Online Capacity Expansion, Optimized Disk, Utilization, S.M.A.R.T and SNMP support, plus features from Adaptec Advanced

• Data Protection Suite including:

1. Hot Space (RAID 5EE)
2. Striped Mirror (RAID 1E)
3. Dual Drive Failure Protection (RAID 6)
4. Copyback Hot Spare

• Advanced RAID Features - Snapshot Backup
• Board dimensions - 24cm x 11.5cm
• Operating temperature - 0 to 55 degrees C
• Mean Time Before Failure (MTBF - time between failures) - 931924 hours at 40 ºC.

Testing

Testing adapters is tricky business. Moreover, we have not yet acquired much experience with SAS. Therefore, it was decided to test the speed of hard drives with SAS interface in comparison with SATA drives. To do this, we used our existing 73 GB Hitachi HUS151473VLS300 15000rpm SAS drives with 16Mb buffer and WD 150GB SATA150 Raptor WD1500ADFD 10000rpm drives with 16Mb buffer. We made a direct comparison of two fast drives, but with different interfaces on two controllers. The disks were tested in the HDTach program, in which the following results were obtained.

Adaptec ASR-48300 12C

Adaptec ASR-4800SAS

It was logical to assume that a SAS hard drive would be faster than a SATA one, although we took the fastest WD Raptor drive for performance evaluation, which can compete in performance with many 15000 rpm SCSI drives. As for the differences between the controllers, they are minimal. Of course, the older model provides more features, but the need for them arises only in the corporate sector for the use of such devices. These enterprise features include special RAID levels and additional cache memory on board the controller. Ordinary home user it is unlikely to install 8 hard drives assembled in a redundant RAID array in a home, albeit up to the very roof of a modified PC - rather, preference will be given to using four drives for a 0 + 1 level array, and the rest will be used for data. This is where the ASR-48300 12C comes in handy. In addition, some overclocker motherboards have a PCI-X interface. The advantage of the model for home use is the relatively affordable price (compared to eight hard drives) of $350 and ease of use (inserted and connected). In addition, 2.5-inch 10K hard drives are of particular interest. These hard drives have lower power consumption, heat up less and take up less space.

conclusions

This is an unusual review for our site and is more about exploring user interest in specialty hardware reviews. Today, not only two unusual RAID controllers from the well-known and well-established manufacturer of server hardware, Adaptec, were considered. It is also an attempt to write the first analytical article on our website.

As for our today's heroes, Adaptec's SAS controllers, we can say that the next two products of the company were a success. The younger model, the $350 ASR-48300, may well take root in a productive home computer and even more so in an entry-level server (or a computer that performs its role). The model has all the prerequisites for this: convenient Adaptec Storage Manager software, support from 8 to 128 disks, work with basic RAID levels.

The older model is designed for serious tasks and, of course, can be used in low-cost servers, but only if there are special requirements for the speed of working with small files and the reliability of information storage, because the card supports all levels of enterprise-class RAID arrays with redundancy and has 128 MB fast DDR2 cache with Error Correction Control (ECC). The cost of the controller is $950.

ASR-48300 12C

Model advantages

• Availability
• Support from 8 to 128 disks
• Ease of use
• Stable work
• Reputation

• PCI-X slot - for greater popularity, only support for the more common PCI-E is missing

ASR-4800SAS

• Stable work
• Manufacturer reputation
• Good functionality
• Availability of upgrades (software and hardware)
• Availability of PCI-E version
• Ease of use
• Support from 8 to 128 disks
• 8 internal SAS links

• Not very suitable for budget and home use sectors.

RAID 6, 5, 1, and 0 array tests with Hitachi SAS-2 drives

Apparently, the days when a decent professional 8-port RAID controller cost quite impressive money are gone. Today there are solutions for the Serial Attached SCSI (SAS) interface, which are very attractive both in terms of price and functionality, and in terms of performance. About one of them - this review.

Controller LSI MegaRAID SAS 9260-8i

Earlier we already wrote about the second generation SAS interface with a transfer rate of 6 Gb / s and a very cheap 8-port LSI SAS 9211-8i HBA controller designed for organizing entry-level storage systems based on the simplest SAS and SATA RAID arrays. drives. The LSI MegaRAID SAS 9260-8i model will be a higher class - it is equipped with more powerful processor with hardware calculation of arrays of levels 5, 6, 50 and 60 (ROC technology - RAID On Chip), as well as a significant amount (512 MB) of on-board SDRAM-memory for efficient data caching. This controller also supports 6Gb/s SAS and SATA interfaces, and the adapter itself is designed for PCI Express x8 Rev. 2.0 bus (5Gb/s per lane), which is theoretically almost enough to meet the needs of 8 high-speed SAS ports. And all this - at a retail price of around $ 500, that is, only a couple of hundred more expensive than the budget LSI SAS 9211-8i. The manufacturer himself, by the way, refers this solution to the MegaRAID Value Line series, that is, economical solutions.

LSIMegaRAID SAS9260-8i 8-port SAS controller and its SAS2108 processor with DDR2 memory

The LSI SAS 9260-8i board has a low profile (MD2 form factor), is equipped with two internal Mini-SAS 4X connectors (each of them allows you to connect up to 4 SAS drives directly or more via port multipliers), is designed for the PCI Express bus x8 2.0 and supports RAID levels 0, 1, 5, 6, 10, 50, and 60, dynamic SAS functionality, and more. etc. The LSI SAS 9260-8i controller can be installed both in 1U and 2U rack servers (Mid and High-End servers) and in ATX and Slim-ATX cases (for workstations). RAID is supported by a hardware - built-in LSI SAS2108 processor (PowerPC core at 800 MHz), understaffed with 512 MB of DDR2 800 MHz memory with ECC support. LSI promises processor data speeds of up to 2.8 GB/s for reading and up to 1.8 GB/s for writing. Among the rich functionality of the adapter, it is worth noting the functions of Online Capacity Expansion (OCE), Online RAID Level Migration (RLM) (expanding the volume and changing the type of arrays on the go), SafeStore Encryption Services and Instant secure erase (encrypting data on disks and securely deleting data ), support for solid state drives (SSD Guard technology), and more. etc. An optional battery module is available for this controller (with it, the maximum operating temperature should not exceed +44.5 degrees Celsius).

LSI SAS 9260-8i Controller Key Specifications

System interface	PCI Express x8 2.0 (5 GT/s), Bus Master DMA
Disk interface	SAS-2 6Gb/s (supports SSP, SMP, STP, and SATA protocols)
Number of SAS ports	8 (2 x4 Mini-SAS SFF8087), supports up to 128 drives via port multipliers
RAID support	levels 0, 1, 5, 6, 10, 50, 60
CPU	LSI SAS2108 ROC (PowerPC @ 800 MHz)
Built-in cache	512 MB ECC DDR2 800 MHz
Energy consumption, no more	24W (+3.3V and +12V supply from PCIe slot)
Operating/Storage Temperature Range	0…+60 °С / −45…+105 °С
Form factor, dimensions	MD2 low-profile, 168×64.4 mm
MTBF value	>2 million h
Manufacturer's Warranty	3 years

Typical applications of the LSI MegaRAID SAS 9260-8i are as follows: a variety of video stations (video on demand, video surveillance, video creation and editing, medical images), high-performance computing and digital data archives, various servers (file, web, mail, databases). In general, the vast majority of tasks solved in small and medium-sized businesses.

In a white-orange box with a frivolously smiling toothy lady's face on the "title" (apparently in order to better lure bearded system administrators and harsh system builders) there is a controller board, brackets for its installation in ATX, Slim-ATX cases, etc., two 4-disk cables with Mini-SAS connectors on one end and regular SATA (without power) on the other (for connecting up to 8 drives to the controller), as well as a CD with PDF documentation and drivers for numerous versions of Windows, Linux (SuSE and RedHat), Solaris and VMware.

LSI MegaRAID SAS 9260-8i boxed controller package (MegaRAID Advanced Services Hardware Key mini card is available upon separate request)

LSI MegaRAID Advanced Services software technologies are available for the LSI MegaRAID SAS 9260-8i controller with a special hardware key (available separately): MegaRAID Recovery, MegaRAID CacheCade, MegaRAID FastPath, LSI SafeStore Encryption Services (their consideration is beyond the scope of this article). In particular, in terms of improving the performance of an array of traditional disks (HDD) using a solid state drive (SSD) added to the system, MegaRAID CacheCade technology will be useful, with which the SSD acts as a second-level cache for the HDD array (an analogue of a hybrid solution for HDD), in individual cases providing an increase in disk subsystem performance up to 50 times. Also of interest is the MegaRAID FastPath solution, which reduces the I / O processing latency of the SAS2108 processor (by disabling HDD optimization), which allows you to speed up the array of multiple solid state drives (SSDs) connected directly to the SAS 9260-8i ports.

It is more convenient to configure, configure and maintain the controller and its arrays in the corporate manager in the operating system environment (the settings in the BIOS Setup menu of the controller itself are not rich enough - only basic functions). In particular, in the manager, in a few mouse clicks, you can organize any array and set its operation policies (caching, etc.) - see screenshots.

Example screenshots of the Windows manager for configuring RAID levels 5 (top) and 1 (bottom).

Testing

To test the base performance of the LSI MegaRAID SAS 9260-8i (without the MegaRAID Advanced Services Hardware Key and related technologies), we used five high-performance SAS drives with a spindle speed of 15K rpm and support for the SAS-2 interface (6 Gb / c) - Hitachi Ultrastar 15K600 HUS156030VLS600 with a capacity of 300 GB.

Hitachi Ultrastar 15K600 hard drive without top cover

This will allow us to test all the basic levels of arrays - RAID 6, 5, 10, 0 and 1, and not only with the minimum number of disks for each of them, but also "for growth", that is, when adding a disk to the second of the 4-channel SAS ports of the ROC chip. Note that the hero of this article has a simplified analogue - a 4-port LSI MegaRAID SAS 9260-4i controller based on the same element base. Therefore, our tests of 4-disk arrays are equally applicable to it.

The maximum payload sequential read/write speed for the Hitachi HUS156030VLS600 is about 200 MB/s (see chart). Average random access time when reading (according to specifications) - 5.4 ms. Built-in buffer - 64 MB.

Hitachi Ultrastar 15K600 HUS156030VLS600 sequential read/write speed chart

The test system was based on Intel processor xeon 3120, motherboard With Intel chipset P45 and 2 GB of DDR2-800 memory. The SAS controller was installed in a PCI Express x16 v2.0 slot. The tests were carried out under the control operating systems Windows XP SP3 Professional and Windows 7 Ultimate SP1 x86 (pure American versions), because their server counterparts (Windows 2003 and 2008 respectively) do not allow some of the benchmarks and scripts we used to work. The tests used were AIDA64, ATTO Disk Benchmark 2.46, Intel IOmeter 2006, Intel NAS Performance Toolkit 1.7.1, C'T H2BenchW 4.13/4.16, HD Tach RW 3.0.4.0, and Futuremark's PCMark Vantage and PCMark05. The tests were carried out both on unallocated volumes (IOmeter, H2BenchW, AIDA64) and on formatted partitions. In the latter case (for NASPT and PCMark), the results were taken both for the physical beginning of the array and for its middle (volumes of arrays with the maximum available capacity were divided into two equal logical partitions). This allows us to more adequately evaluate the performance of solutions, since the fastest initial sections of volumes, on which file benchmarks are carried out by most browsers, often do not reflect the situation on other sections of the disk, which can also be used very actively in real work.

All tests were performed five times and the results were averaged. We'll take a closer look at our updated methodology for evaluating professional disk solutions in a separate article.

It remains to add that in this test we used the controller firmware version 12.12.0-0036 and drivers version 4.32.0.32. Write and read caching for all arrays and drives has been enabled. Perhaps the use of more modern firmware and drivers saved us from the oddities seen in the results of early tests of the same controller. In our case, such incidents were not observed. However, we also do not use the FC-Test 1.0 script, which is very doubtful in terms of the reliability of the results (which in certain cases the same colleagues “want to call confusion, vacillation and unpredictability”) in our package, since we have repeatedly noticed its failure on some file patterns ( in particular, sets of many small, less than 100 KB files).

The charts below show the results for 8 array configurations:

1. RAID 0 of 5 disks;
2. RAID 0 of 4 drives;
3. RAID 5 of 5 disks;
4. RAID 5 of 4 drives;
5. RAID 6 of 5 disks;
6. RAID 6 of 4 drives;
7. RAID 1 of 4 drives;
8. RAID 1 of 2 drives.

By a RAID 1 array of four disks (see the screenshot above), LSI obviously means a stripe + mirror array, usually referred to as RAID 10 (this is also confirmed by the test results).

Test results

In order not to overload the review web page with a countless set of diagrams, sometimes uninformative and tiring (which some "rabid colleagues" often sin :)), we have summarized the detailed results of some tests in table. Those who wish to analyze the subtleties of our results (for example, to find out the behavior of the defendants in the most critical tasks for themselves) can do this on their own. We will focus on the most important and key test results, as well as on average indicators.

First, let's look at the results of "purely physical" tests.

The average random access time for a read on a single Hitachi Ultrastar 15K600 HUS156030VLS600 drive is 5.5 ms. However, when organizing them into arrays, this indicator changes slightly: it decreases (due to effective caching in the LSI SAS9260 controller) for “mirror” arrays and increases for all the others. The largest growth (about 6%) is observed for arrays of level 6, since in this case the controller has to simultaneously access the largest number disks (to three for RAID 6, two for RAID 5, and one for RAID 0, since the access in this test occurs in blocks of only 512 bytes, which is significant smaller size array striping blocks).

The situation with random access to arrays during writing (blocks of 512 bytes) is much more interesting. For a single disk, this parameter is about 2.9 ms (without caching in the host controller), however, in arrays on the LSI SAS9260 controller, we see a significant decrease in this indicator due to good write caching in the 512 MB SDRAM buffer of the controller. Interestingly, the most dramatic effect is obtained for RAID 0 arrays (random access time during writes drops by almost an order of magnitude compared to a single drive)! This should undoubtedly have a beneficial effect on the performance of such arrays in a number of server tasks. At the same time, even on arrays with XOR calculations (that is, a high load on the SAS2108 processor), random write accesses do not lead to an obvious performance drop - again thanks to the powerful controller cache. Naturally, RAID 6 is slightly slower here than RAID 5, but the difference between them is essentially insignificant. I was somewhat surprised by the behavior of a single “mirror” in this test, which showed the slowest random access when writing (perhaps this is a “feature” of the microcode of this controller).

Linear (sequential) read and write speed graphs (in large blocks) for all arrays do not have any peculiarities (they are almost identical for reading and writing, provided controller write caching is enabled) and all of them are scaled according to the number of disks participating in parallel in the “useful » process. That is, for five-disk RAID 0 disks, the speed "fivefolds" relative to a single disk (reaching 1 GB / s!), for five-disk RAID 5 it "quadruples", for RAID 6 - "triples" (triples, of course :)), for a RAID 1 of four disks, it doubles (no "y2eggs"! :)), and for a simple mirror, it duplicates the graphs of a single disk. This pattern is clearly visible, in particular, in terms of the maximum reading and writing speed of real large (256 MB) files in large blocks (from 256 KB to 2 MB), which we will illustrate with a diagram of the ATTO Disk Benchmark 2.46 test (the results of this test for Windows 7 and XP are almost identical).

Here, only the case of reading files on a RAID 6 array of 5 disks unexpectedly fell out of the general picture (the results were repeatedly rechecked). However, for reading in blocks of 64 KB, the speed of this array is gaining its 600 MB / s. So let's write off this fact as a "feature" of the current firmware. We also note that when writing real files, the speed is slightly higher due to caching in a large controller buffer, and the difference with reading is more noticeable, the lower the real linear speed of the array.

As for the interface speed, usually measured in terms of buffer writes and reads (multiple accesses to the same address of a disk volume), here we have to state that it turned out to be the same for almost all arrays due to the inclusion of the controller cache for these arrays (see . table). Thus, the recording performance for all participants in our test amounted to approximately 2430 MB / s. Note that the PCI Express x8 2.0 bus theoretically gives a speed of 40 Gb / s or 5 Gb / s, however, according to useful data, the theoretical limit is lower - 4 Gb / s, which means that in our case the controller really worked according to version 2.0 of the PCIe bus. Thus, the 2.4 GB / s we measured is, obviously, the real bandwidth of the controller's on-board memory (DDR2-800 memory with a 32-bit data bus, as can be seen from the configuration of the ECC chips on the board, theoretically gives up to 3.2 GB/s). When reading arrays, caching is not as "comprehensive" as when writing, therefore, the speed of the "interface" measured in utilities is, as a rule, lower than the speed of reading the controller's cache memory (typical 2.1 GB / s for arrays of levels 5 and 6) , and in some cases it "drops" to the read speed of the buffer of the hard drives themselves (about 400 MB / s for a single hard drive, see the graph above), multiplied by the number of "consecutive" drives in the array (this is exactly the cases of RAID 0 and 1 from our results).

Well, we figured out the "physics" in the first approximation, it's time to move on to the "lyrics", that is, to the tests of the "real" application boys. By the way, it will be interesting to find out whether the performance of arrays scales when performing complex user tasks as linearly as it scales when reading and writing large files (see the ATTO test diagram just above). The inquisitive reader, I hope, has already been able to predict the answer to this question.

As a “salad” to our “lyrical” part of the meal, we will serve desktop-based disk tests from the PCMark Vantage and PCMark05 packages (under Windows 7 and XP, respectively), as well as a similar “track” application test from the H2BenchW 4.13 package of the authoritative German magazine C'T. Yes, these tests were originally designed to evaluate desktop and low-cost workstation hard drives. They emulate the performance of typical tasks of an advanced personal computer on disks - working with video, audio, photoshop, antivirus, games, swap files, installing applications, copying and writing files, etc. Therefore, their results should not be taken in the context of this article. as the ultimate truth - after all, other tasks are more often performed on multi-disk arrays. Nevertheless, in light of the fact that the manufacturer himself positions this RAID controller, including for relatively inexpensive solutions, such a class of test tasks is quite capable of characterizing a certain proportion of applications that will actually be run on such arrays (the same work with video, professional graphics processing, swapping OS and resource-intensive applications, copying files, antivirus, etc.). Therefore, the importance of these three comprehensive benchmarks in our overall package should not be underestimated.

In the popular PCMark Vantage, on average (see diagram), we observe a very remarkable fact - the performance of this multi-disk solution almost does not depend on the type of array used! By the way, within certain limits, this conclusion is also valid for all individual test tracks (task types) included in the PCMark Vantage and PCMark05 packages (see the table for details). This may mean either that the controller firmware algorithms (with cache and disks) almost do not take into account the specifics of the operation of applications of this type, or that the main part of these tasks is performed in the cache memory of the controller itself (and most likely we observe a combination of these two factors ). However, for the latter case (that is, the execution of tracks to a large extent in the RAID controller cache), the average performance of solutions is not so high - compare these data with the test results of some "desktop" ("chipset") 4-disk RAID 0 arrays and 5 and inexpensive single SSDs on the SATA 3 Gb / s bus (see review). If, compared to a simple "chipset" 4-disk RAID 0 (and on twice slower hard drives than the Hitachi Ultrastar 15K600 used here), LSI SAS9260 arrays are less than twice as fast in PCMark tests, then relatively not even the fastest "budget" single SSD all of them definitely lose! The results of the PCMark05 disk test give a similar picture (see table; it makes no sense to draw a separate diagram for them).

A similar picture (with some reservations) for LSI SAS9260 arrays can be seen in another "track" application benchmark - C'T H2BenchW 4.13. Here, only the two slowest (in terms of structure) arrays (RAID 6 of 4 disks and a simple “mirror”) are noticeably behind all other arrays, the performance of which, obviously, reaches that “sufficient” level when it no longer rests on the disk subsystem, and in the efficiency of the SAS2108 processor with the controller cache for these complex access sequences. And in this context, we can be pleased that the performance of arrays based on LSI SAS9260 in tasks of this class almost does not depend on the type of array used (RAID 0, 5, 6 or 10), which allows you to use more reliable solutions without compromising the final performance.

However, “not everything is Maslenitsa to the cat” - if we change the tests and check the operation of arrays with real files on file system NTFS, the picture will change dramatically. Thus, in the Intel NASPT 1.7 test, many of whose “pre-installed” scenarios are quite directly related to tasks typical for computers equipped with the LSI MegaRAID SAS9260-8i controller, the array disposition is similar to what we observed in the ATTO test when reading and writing large files - the speed increases proportionally as the "linear" speed of the arrays grows.

In this chart, we show an average of all NASPT tests and patterns, while in the table you can see the detailed results. Let me emphasize that we ran NASPT both under Windows XP (as numerous browsers usually do) and under Windows 7 (which, due to certain features of this test, is done less frequently). The fact is that Seven (and its "big brother" Windows 2008 Server) use more aggressive algorithms of their own caching when working with files than XP. In addition, copying large files in the "Seven" occurs mainly in blocks of 1 MB (XP, as a rule, operates in blocks of 64 KB). This leads to the fact that the results of the "file" Intel NASPT test differ significantly in Windows XP and Windows 7 - in the latter they are much higher, sometimes more than twice! By the way, we compared the results of NASPT (and other tests of our package) under Windows 7 with 1 GB and 2 GB of installed system memory (there is information that with large amounts of system memory, caching of disk operations in Windows 7 increases and NASPT results become even higher) , however, within the measurement error, we did not find any difference.

Arguments about what OS (in terms of caching policies, etc.) is “better” to test disks and RAID controllers, we leave for the discussion thread of this article. We believe that it is necessary to test drives and solutions based on them in conditions as close as possible to real situations their operation. That is why, in our opinion, the results obtained by us for both operating systems are of equal value.

But back to the NASPT average performance chart. As you can see, the difference between the fastest and slowest of the arrays we tested here is on average a little less than three times. This, of course, is not a five-fold gap, as when reading and writing large files, but it is also very noticeable. The arrays are actually located in proportion to their linear speed, and this cannot but rejoice: it means that the LSI SAS2108 processor processes data quite quickly, almost without creating bottlenecks when arrays of levels 5 and 6 are actively working.

In fairness, it should be noted that NASPT also has patterns (2 out of 12) in which the same picture is observed as in PCMark with H2BenchW, namely that the performance of all tested arrays is almost the same! These are Office Productivity and Dir Copy to NAS (see table). This is especially evident under Windows 7, although for Windows XP the trend of "convergence" is obvious (compared to other patterns). However, in PCMark with H2BenchW there are patterns where there is an increase in array performance in proportion to their linear speed. So everything is not as simple and unambiguous as some might like.

At first, I wanted to discuss a chart with the overall performance of arrays, averaged over all application tests (PCMark + H2BenchW + NASPT + ATTO), that is, this one:

However, there is nothing much to discuss here: we see that the behavior of arrays on the LSI SAS9260 controller in tests that emulate the operation of certain applications can vary dramatically depending on the scenarios used. Therefore, it is better to draw conclusions about the benefits of a particular configuration based on what tasks you are going to perform at the same time. And one more professional test can significantly help us in this - synthetic patterns for IOmeter, emulating this or that load on the storage system.

Tests in IOmeter

In this case, we will omit the discussion of numerous patterns that carefully measure the speed of work depending on the size of the access block, the percentage of writes, the percentage of random accesses, etc. This is, in fact, pure synthetics, providing little useful practical information and of interest rather purely theoretically. After all, we have already clarified the main practical points regarding “physics” above. It is more important for us to focus on patterns that emulate real work - servers of various types, as well as file operations.

To emulate servers such as File Server, Web Server and DataBase (database server), we used the well-known patterns of the same name, proposed at one time by Intel and StorageReview.com. For all cases, we tested arrays with a command queue depth (QD) from 1 to 256 with a step of 2.

In the Database pattern, which uses random disk accesses in blocks of 8 KB within the entire array, one can observe a significant advantage of arrays without parity (that is, RAID 0 and 1) with a command queue depth of 4 or higher, while all parity-checked arrays (RAID 5 and 6) demonstrate very similar performance (despite a twofold difference between them in the speed of linear accesses). The situation is easily explained: all arrays with parity showed similar values ​​in tests for the average random access time (see the diagram above), and this parameter mainly determines the performance in this test. It is interesting that the performance of all arrays increases almost linearly with increasing command queue depth up to 128, and only at QD=256, in some cases, you can see a hint of saturation. The maximum performance of arrays with parity at QD=256 was about 1100 IOps (operations per second), that is, the LSI SAS2108 processor spends less than 1 ms to process one portion of data of 8 KB (about 10 million single-byte XOR operations per second for RAID 6 ; of course, the processor also performs other I/O and cache tasks in parallel).

In pattern file server, which uses blocks of different sizes for random read and write accesses to the array within its entire volume, we observe a picture similar to the DataBase, with the difference that here five-disk arrays with parity (RAID 5 and 6) noticeably outperform their 4-disk arrays. analogues and at the same time demonstrate almost identical performance (about 1200 IOps at QD=256)! Apparently, adding a fifth drive to the second of the two 4-lane SAS ports on the controller somehow optimizes the computational load on the processor (due to I / O operations?). It might be worth comparing 4-disk arrays in terms of speed when the drives are connected in pairs to different Mini-SAS connectors of the controller in order to identify the optimal configuration for organizing arrays on the LSI SAS9260, but this is a task for another article.

In the web server pattern, where, according to the intention of its creators, there are no disk write operations as a class (and hence the calculation of XOR functions for writing), the picture becomes even more interesting. The fact is that all three five-disk arrays from our set (RAID 0, 5 and 6) show identical performance here, despite the noticeable difference between them in terms of linear reading and parity calculations! By the way, the same three arrays, but of 4 disks, are also identical in speed to each other! And only RAID 1 (and 10) falls out of the picture. Why this happens is difficult to judge. Perhaps the controller has very efficient algorithms for selecting "good drives" (that is, those of five or four drives from which the necessary data comes first), which in the case of RAID 5 and 6 increases the likelihood of data arriving from the platters earlier, preparing the processor in advance for necessary calculations (think of the deep command queue and the large DDR2-800 buffer). And this can ultimately compensate for the delay associated with XOR calculations and equalize them in “chance” with “simple” RAID 0. In any case, the LSI SAS9260 controller can only be praised for its extremely high results (about 1700 IOps for 5-disk arrays with QD=256) in the Web Server pattern for arrays with parity. Unfortunately, the fly in the ointment was the very poor performance of the two-disk “mirror” in all these server patterns.

The Web Server pattern is echoed by our own pattern, which emulates random reading of small (64 KB) files within the entire array space.

Again, the results were combined into groups - all 5-disk arrays are identical to each other in terms of speed and lead in our “race”, 4-disk RAID 0, 5 and 6 also cannot be distinguished from each other in terms of performance, and only “DSLRs” fall out of the general masses (by the way, a 4-disk "mirror", that is, RAID 10 is faster than all other 4-disk arrays - apparently, due to the same "choosing a good disk" algorithm). We emphasize that these patterns are valid only for a large command queue depth, while with a small queue (QD=1-2), the situation and leaders can be completely different.

Everything changes when servers work with large files. In the conditions of modern "heavier" content and new "optimized" operating systems such as Windows 7, 2008 Server, etc. working with megabyte files and 1 MB data blocks is becoming increasingly important. In this situation, our new pattern, which emulates random reading of 1-MB files within the entire disk (details of the new patterns will be described in a separate article on the methodology), comes in handy in order to more fully assess the server potential of the LSI SAS9260 controller.

As you can see, the 4-disk "mirror" here no longer leaves anyone hope for leadership, clearly dominating in any order of commands. Its performance also first grows linearly with the command queue depth, but with QD=16 for RAID 1, it saturates (about 200 MB/s). A little “later” (at QD=32) “saturation” of performance occurs in arrays that are slower in this test, among which “silver” and “bronze” have to be given to RAID 0, and arrays with parity turn out to be outsiders, losing even before a brilliant RAID 1 of two drives, which turns out to be unexpectedly good. This leads us to the conclusion that even when reading, the XOR computational load on the LSI SAS2108 processor when working with large files and blocks (arranged randomly) is very burdensome for him, and for RAID 6, where it actually doubles, sometimes even exorbitant - the performance of solutions barely exceeds 100 MB / s, that is, 6-8 times lower than with linear reading! "Excessive" RAID 10 is clearly more profitable to use here.

When accidentally writing small files, the picture is again strikingly different from what we saw earlier.

The fact is that here the performance of arrays practically does not depend on the depth of the command queue (obviously, the huge cache of the LSI SAS9260 controller and rather big caches of the hard drives themselves affect), but it changes dramatically with the type of array! The undisputed leaders here are "simple" ones for the RAID 0 processor, and "bronze" with more than a twofold loss to the leader - in RAID 10. All arrays with parity formed a very close single group with a two-disk SLR ), three times losing to the leaders. Yes, this is definitely a heavy load on the controller's processor. However, frankly speaking, I did not expect such a “failure” from the SAS2108. Sometimes even a soft RAID 5 on a “chipset” SATA controller (with caching using Windows and calculation using the PC’s central processor) is able to work faster ... However, the controller still outputs “its” 440-500 IOps stably - compare this with chart on the average write access time at the beginning of the results section.

Switching to random writing of large files of 1 MB each leads to an increase in absolute speed indicators (for RAID 0 - almost to the values ​​\u200b\u200bfor random reading of such files, that is, 180-190 MB / s), but the overall picture remains almost the same - arrays with parity many times slower than RAID 0.

The picture for RAID 10 is curious - its performance drops with increasing command queue depth, although not much. For other arrays, there is no such effect. The two-disk "mirror" here again looks modest.

Now let's look at patterns in which files are read and written to disk in equal numbers. Such loads are typical, in particular, for some video servers or during active copying / duplication / backup of files within the same array, as well as in the case of defragmentation.

First - files of 64 KB randomly throughout the array.

Here, some similarity with the results of the DataBase pattern is obvious, although the absolute speeds of arrays are three times higher, and even with QD=256, some performance saturation is already noticeable. A higher (compared to the DataBase pattern) percentage of write operations in this case leads to the fact that arrays with parity and a two-disk “mirror” become obvious outsiders, significantly inferior in speed to RAID 0 and 10 arrays.

When switching to 1 MB files, this pattern generally remains, although the absolute speeds approximately triple, and RAID 10 becomes as fast as a 4-disk stripe, which is good news.

The last pattern in this article will be the case of sequential (as opposed to random) reading and writing large files.

And here already many arrays manage to accelerate to very decent speeds in the region of 300 MB / s. And although the gap between the leader (RAID 0) and the outsider (double-disk RAID 1) remains more than twofold (note that this gap is fivefold for linear reads or writes!), RAID 5, which is among the top three, and the other XOR arrays that have pulled themselves up, do not may not be encouraging. After all, judging by the list of applications of this controller, which LSI itself gives (see the beginning of the article), many target tasks will use this particular nature of array accesses. And it's definitely worth considering.

In conclusion, I will give a final diagram in which the indicators of all the above-mentioned IOmeter test patterns are averaged (geometrically over all patterns and command queues, without weight coefficients). It is curious that if the averaging of these results within each pattern is carried out arithmetically with weight coefficients of 0.8, 0.6, 0.4, and 0.2 for command queues 32, 64, 128, and 256, respectively (which conventionally depth of the command queue in the overall operation of drives), then the final (for all patterns) normalized array performance index within 1% will coincide with the geometric mean.

So, the average “hospital temperature” in our patterns for the IOmeter test shows that there is no way out of “physics with math” - RAID 0 and 10 are definitely in the lead. in some cases, decent performance, in general, it cannot "reach" such arrays to the level of a simple "stripe". At the same time, it is interesting that 5-disk configurations clearly add compared to 4-disk configurations. In particular, 5-disk RAID 6 is unambiguously faster than 4-disk RAID 5, although in terms of "physics" (random access time and linear access speed) they are virtually identical. The two-disk “mirror” was also disappointing (on average, it is equivalent to a 4-disk RAID 6, although two XOR calculations per data bit are not required for a mirror). However, a simple "mirror" is obviously not a target array for a sufficiently powerful 8-port SAS controller with a large cache and a powerful processor "on board". :)

Price Information

The LSI MegaRAID SAS 9260-8i 8-port SAS controller with a complete set is offered at a price of around $500, which can be considered quite attractive. Its simplified 4-port counterpart is even cheaper. A more accurate current average retail price of the device in Moscow, relevant at the time you read this article:

LSI SAS 9260-8i	LSI SAS 9260-4i
$571()	$386()

Conclusion

Summing up what has been said above, we can conclude that we will not dare to give unified recommendations “for everyone” on the 8-port LSI MegaRAID SAS9260-8i controller. Everyone should draw their own conclusions about the need to use it and configure certain arrays with its help - strictly based on the class of tasks that are supposed to be launched. The fact is that in some cases (on some tasks) this inexpensive "megamonster" is able to show outstanding performance even on arrays with double parity (RAID 6 and 60), but in other situations, the speed of its RAID 5 and 6 clearly leaves much to be desired. . And the salvation (almost universal) will be only a RAID 10 array, which can be organized almost with the same success on cheaper controllers. However, it is often thanks to the processor and cache memory SAS9260-8i that the RAID 10 array behaves here no slower than a "stripe" of the same number of disks, while ensuring high reliability of the solution. But what you should definitely avoid with the SAS9260-8i is a two-disk "reflex" and 4-disk RAID 6 and 5 - these are obviously suboptimal configurations for this controller.

Thanks to Hitachi Global Storage Technologies
for hard drives provided for testing.

If there are a couple of computer disks, connecting them is simple. But if you want a lot of disks, there are features. On the KDPV SAS cable with Ali, which has already slipped in the past, was so unexpectedly warmly received by the community. Thanks, comrades. I will try to touch on a topic that is potentially useful to a slightly wider circle. Although specific. I'll start with this cable and a mandatory program, but only for the seed. Different pieces of the puzzle have to be collected in different places.
I want to warn you right away that the text turned out to be dense and rather heavy. Forcing yourself to read and understand all this is certainly not necessary. Lots of pictures!

Someone say 9 bucks for a dumb cable? What to do, in everyday life this is used extremely rarely, and for industrial things, circulations are lower, and prices are higher. For a complex SAS cable and a hundred or two bucks, they can set it up without batting an eye. So the Chinese are reducing it even more :)

Delivery and packaging

Ordered May 6, 2017, received May 17 - just a rocket. The track was.

The usual gray package, inside another one - quite enough, the goods are not fragile.

Specification

Male-male SFF-8482 SAS 29 pin cable.
Length 50 cm
Net weight 66 g

Seller's picture

The actual appearance, as you can see, is different

For extra plastic, the seller received 4 stars instead of 5, but does not affect performance.

About SAS and SATA connectors

What is SFF-8482 and what is it eaten with? Firstly, this is the most massive connector on SAS devices (), for example, on my tape drive

And the SFF-8482 fits perfectly on a SATA drive (but not vice versa)


Compare, SATA has a gap between data and power. And at SAS it is filled with plastic. Therefore, the SATA connector on the SAS device will not fit.

Of course, this makes sense. SAS and SATA signals are different. And the SATA controller will not be able to work with the SAS device. A SAS - the controller will be able to do both (although there is advice not to mix under certain circumstances, at home it is hardly real)

SAS controllers and expanders

So what, the reader will ask. What do I gain from such compatibility? SATA controllers are enough for me!

True truth! If enough - at this point you can stop reading. The question was what to do if there are A LOT of disks?

This is how a simple SAS controller from my zip looks like - DELL H200.


Mine is flashed in HBA, that is, all axle disks are visible separately

And this is an ancient SAS RAID HP

Both have internal connectors (called sff 8087 or, more often, miniSAS) and one external - sff 8088

How many disks can be connected to one miniSAS? The answer depends. Blunt cable - 4pcs, that is, 8 for such a controller. The cable from my ZIP looks like this

On one end miniSAS, on the other - 4pcs SATA (and one more connector, about it below)

But you can take a miniSAS-miniSAS cable and connect it to an expander, that is, a port multiplier. And the controller will pull up to 256 (two hundred and fifty six) disks. Moreover, the channel speed is enough for dozens of disks - for sure.
Expander as a separate card looks, for example, like my Chenbrough

And it can be soldered on a disk basket. Then only one miniSAS channel can go into it (or maybe more). Here are the cables.


Agree, cable management is somewhat simplified :)

Baskets

It is clear that disks can work fine without special baskets. But sometimes baskets can be useful.

This is how the SATA basket of the old Supermicro model looks like. Can be found for 1000 r, but rather for 5+ thousand.


Her disc tray


View from the inside, you can see that there are SATA connectors.


If the SAS basket is even better, there are fewer wires. If SCSI or FC - you will not be able to use it. I took one 19 "FC for a test - I did nothing useful. True, there was non-ferrous metal scrap almost for the money I bought it for.


Rear view, we see 4 SATA, 2 MOLEX and the same port that was on the cable. Designed to control disk activity LED.

This is how one of the simplest baskets looks like (there are many different models, but similar ones)


These are not sold anymore, so the details are not important. Just a piece of metal with shock absorbers and Carlson in front.

This is what it looked like in 2013


The cardboard crutch at the bottom and the third basket were only there for a moment to transfer data from 2T disks to 4T. Since then it has been open 24/7.

I have SAS+SATA

More precisely, it worked before I needed to connect the tape drive. First of all, I plugged in a second SAS controller, bought a miniSAS cable for sff 8482, something like this

And turned it on. Everything worked, but in 24/7 mode, every watt costs money. I was looking for adapters from sff 8482 to SATA, but the solution turned out to be even simpler. Do you remember that a SATA drive is connected to a SAS sff 8482?

Now I also remember, but then I was stupid for a couple of months :) And then I took out an extra controller, switched one of the disks to the SATA chipset port, the other three to sff 8482. I had to change the power connection, there was a Molex-SATA splitter, I had to buy on Ali Molex - Lots of Molex. like this


, everything is fine.

And the tape drive moved to another building using the monitored cable. But this is a separate song, but, guard, I feel tired :)

Where is the best place to find all this?

Prices for new server hardware for the home are prohibitive. So bu, including spare parts from equipment being decommissioned.
Cables can be found locally. For comparable money on e-bay. On Ali - somewhat less likely, but there are exceptions - I bought it.
Controllers- primarily on e-bay, and from Europe. It is possible from the USA, it is much cheaper there, if you somehow solve the issue with delivery. Can be found in the homeland - Avito. (On a lump - expensive). Buying in China is very dangerous. A lot of complaints about the fake from the rejection. Either it works or it doesn't. You can't prove anything to anyone.
Baskets it is wiser to search locally. There are even options for the simplest baskets to buy new ones. Simple baskets without electronics can be taken in China and Europe and at a flea market. Baskets with expanders - see the point about controllers.

IMPORTANT Getting confused is easier than getting lost in the woods. Consult on the forum. SAS is different -3, 6 and 12 Gb / s. Some controllers are sewn into something that can be used with desktop hardware, others are not, others will not heal at all anywhere except for the mother of the native manufacturer. And so on.

On the trunk I'm MikeMac

PS If this was Captain Obvious's performance for you, I apologize for wasting time.
If bullshit - all the more my sincere apologies. It is difficult to balance, everyone has their own wishes, tasks and initial ones.

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