This article will discuss what allows you to connect HDD to the computer, namely, about the interface hard drive. More precisely, about interfaces hard drives, because a great variety of technologies for connecting these devices have been invented over the entire period of their existence, and the abundance of standards in this area can confuse an inexperienced user. However, first things first.
Hard drive interfaces (or, strictly speaking, interfaces external drives, since not only can act as them, but also other types of drives, for example, optical disc drives) are designed to exchange information between these devices external memory and motherboard. Hard drive interfaces, no less than the physical parameters of drives, affect many of the drive's performance and performance. In particular, drive interfaces determine such parameters as the speed of data exchange between the hard drive and the motherboard, the number of devices that can be connected to the computer, the ability to create disk arrays, the possibility of hot plugging, support for NCQ and AHCI technologies, etc. . It also depends on the interface of the hard drive which cable, cord or adapter you need to connect it to the motherboard.
SCSI - Small Computer System Interface
The SCSI interface is one of the oldest interfaces developed for connecting drives in personal computers. This standard appeared in the early 1980s. One of its developers was Alan Shugart, also known as the inventor of floppy disk drives.
The appearance of the SCSI interface on the board and the cable connecting to it
The SCSI standard (traditionally, this abbreviation is read in Russian transcription as "skazi") was originally intended for use in personal computers, as evidenced even by the name of the format - Small Computer System Interface, or a system interface for small computers. However, it so happened that drives of this type were used mainly in top-class personal computers, and later in servers. This was due to the fact that, despite the successful architecture and a wide set of commands, the technical implementation of the interface was rather complicated and was not suitable for mass PCs in terms of cost.
However, this standard had a number of features not available for other types of interfaces. For example, a cord for connecting Small Computer System Interface devices can have a maximum length of 12 m and a data transfer rate of 640 MB/s.
Like the IDE interface that appeared a little later, the SCSI interface is parallel. This means that the interface uses buses that transmit information over several conductors. This feature was one of the limiting factors for the development of the standard, and therefore, a more advanced, serial SAS standard (from Serial Attached SCSI) was developed as its replacement.
SAS - Serial Attached SCSI
This is how the SAS interface of the server disk looks like
Serial Attached SCSI was developed as an improvement on the rather old Small Computers System Interface hard drive interface. Despite the fact that Serial Attached SCSI uses the main advantages of its predecessor, nevertheless, it has many advantages. Among them it is worth noting the following:
- Use of a common bus by all devices.
- The serial communication protocol used by SAS allows fewer signal lines to be used.
- There is no need for bus termination.
- Virtually unlimited number of connected devices.
- Higher bandwidth (up to 12 Gbps). Future implementations of the SAS protocol are expected to support data rates up to 24 Gbps.
- Ability to connect drives with Serial ATA interface to the SAS controller.
Typically, Serial Attached SCSI systems are built from several components. The main components include:
- target devices. This category includes the actual drives or disk arrays.
- Initiators are chips designed to generate requests to target devices.
- Data delivery system - cables connecting target devices and initiators
Serial Attached SCSI connectors come in various shapes and sizes, depending on the type (external or internal) and SAS versions. Below are the internal SFF-8482 connector and the external SFF-8644 connector designed for SAS-3:
Left - internal connector SAS SFF-8482; On the right is an external SAS SFF-8644 connector with a cable.
A few examples of the appearance of SAS cords and adapters: HD-Mini SAS cord and SAS-Serial ATA adapter cord.
Left - HD Mini SAS cord; Right - adapter cable from SAS to Serial ATA
Firewire - IEEE 1394
Today it is quite common to see hard drives with Firewire interface. Although the Firewire interface can connect any type of peripherals, and it's not a dedicated interface designed exclusively for connecting hard drives, but Firewire has a number of features that make it extremely convenient for this purpose.
FireWire - IEEE 1394 - laptop view
The Firewire interface was developed in the mid-1990s. The beginning of the development was laid by the well-known company Apple, which needed its own, different from USB, bus for connecting peripheral equipment, primarily multimedia. The specification describing the operation of the Firewire bus is called IEEE 1394.
Firewire is one of the most commonly used high-speed serial front-end bus formats today. The main features of the standard include:
- Ability to hot connect devices.
- Open bus architecture.
- Flexible topology for connecting devices.
- Widely varying data transfer rate - from 100 to 3200 Mbps.
- The ability to transfer data between devices without the participation of a computer.
- Possibility of organization local networks with the help of a tire.
- Bus power transmission.
- A large number of connected devices (up to 63).
To connect hard drives (usually through external hard drive cases) via the Firewire bus, as a rule, a special SBP-2 standard is used, which uses the Small Computers System Interface protocol command set. It is possible to connect Firewire devices to a regular USB connector, but this requires a special adapter.
IDE - Integrated Drive Electronics
The abbreviation IDE is undoubtedly familiar to most personal computer users. The interface standard for connecting IDE hard drives was developed by a well-known hard drive manufacturer - western digital. The advantage of IDE over other interfaces that existed at that time, in particular, the Small Computers System Interface, as well as the ST-506 standard, was that there was no need to install a hard disk controller on the motherboard. The IDE standard meant installing the drive controller on the case of the drive itself, and only the host interface adapter for connecting IDE drives remained on the motherboard.
IDE interface on motherboard
This innovation has improved the performance of the IDE drive due to the fact that the distance between the controller and the drive itself has been reduced. In addition, the installation of an IDE controller inside the hard drive enclosure made it possible to somewhat simplify both motherboards and the production of hard drives themselves, since the technology gave manufacturers freedom in terms of optimal organization of the drive's operation logic.
The new technology was originally called Integrated Drive Electronics. Subsequently, a standard describing it, called ATA, was developed. This name comes from the last part of the name of the PC/AT computer family by adding the word Attachment.
For connecting hard drive or other device, such as an optical drive that supports Integrated Drive Electronics Technology, to the motherboard, a dedicated IDE cable is used. Since ATA refers to parallel interfaces (which is why it is also called Parallel ATA or PATA), that is, interfaces that provide simultaneous data transfer over several lines, its data cable has a large number of conductors (usually 40, and in latest versions protocol, it was possible to use an 80-core cable). Regular data cable for this standard has a flat and wide appearance, but there are also round cables. The power cable for Parallel ATA drives has a 4-pin connector and is connected to the computer's power supply.
The following are examples of an IDE cable and a round PATA data cable:
The appearance of the interface cable: on the left - flat, on the right in a round sheath - PATA or IDE.
Due to the relative cheapness of Parallel ATA drives, the ease of implementing an interface on the motherboard, and the ease of installation and configuration of PATA devices for the user, drives such as Integrated Drive Electronics ousted devices of other types of interface from the market of hard drives for low-end personal computers for a long time.
However, the PATA standard also has a number of disadvantages. First of all, this is a limitation on the length that a Parallel ATA data cable can have - no more than 0.5 m. In addition, the parallel organization of the interface imposes a number of restrictions on top speed data transmission. Does not support the PATA standard and many advanced features that other types of interfaces have, such as hot plugging devices.
SATA - Serial ATA
View of the SATA interface on the motherboard
The SATA (Serial ATA) interface, as the name suggests, is an improvement on ATA. This improvement consists, first of all, in the conversion of the traditional parallel ATA (Parallel ATA) into a serial interface. However, the differences between the Serial ATA standard and the traditional one are not limited to this. In addition to changing the type of data transfer from parallel to serial, the connectors for data transfer and power supply have also changed.
Below is the SATA data cord:
Data cable for SATA interface
This made it possible to use a much longer cable and increase the data transfer rate. However, the downside was the fact that PATA devices, which before the advent of SATA were present on the market in huge quantities, it became impossible to directly connect to the new connectors. True, most new motherboards still have the old connectors and support the connection of old devices. However, the reverse operation - connecting a new type of drive to an old motherboard usually causes much more problems. For this operation, the user usually requires a Serial ATA to PATA adapter. The power cable adapter usually has a relatively simple design.
Serial ATA to PATA power adapter:
On the left is a general view of the cable; enlarged on the right appearance PATA and Serial ATA connectors
More complicated, however, is the situation with a device such as an adapter for connecting a serial interface device to a parallel interface connector. Typically, this type of adapter is made in the form of a small microcircuit.
Appearance of a universal bidirectional adapter between SATA - IDE interfaces
At present, the Serial ATA interface has practically supplanted Parallel ATA, and PATA drives can now be found mainly only in fairly old computers. Another feature of the new standard, which ensured its wide popularity, was support for .
Type of adapter from IDE to SATA
You can tell a little more about NCQ technology. The main advantage of NCQ is that it allows you to use ideas that have long been implemented in the SCSI protocol. In particular, NCQ supports a system for ordering read/write operations coming to multiple drives installed in the system. Thus, NCQ can significantly improve the performance of drives, especially hard drive arrays.
Type of adapter from SATA to IDE
To use NCQ, the technology must be supported by the hard drive as well as the motherboard host adapter. Almost all adapters that support AHCI also support NCQ. In addition, some older proprietary adapters also support NCQ. Also, NCQ requires support from outside to work. operating system.
eSATA - External SATA
Separately, it is worth mentioning the eSATA (External SATA) format, which seemed promising at the time, but was not widely used. As you might guess from the name, eSATA is a type of Serial ATA designed to connect exclusively external drives. The eSATA standard offers for external devices most of the features of the standard, i.e. internal Serial ATA, in particular, the same system of signals and commands and the same high speed.
eSATA connector on a laptop
However, eSATA also has some differences from the internal bus standard that gave rise to it. In particular, eSATA supports a longer data cable (up to 2m) and also has higher storage power requirements. In addition, eSATA connectors are somewhat different from standard Serial ATA connectors.
Compared to other external buses such as USB and Firewire, however, eSATA has one significant drawback. If these buses allow the device to be powered through the bus cable itself, then the eSATA drive requires special power connectors. Therefore, despite the relatively high data transfer rate, eSATA is currently not very popular as an interface for connecting external drives.
Conclusion
Information stored on a hard disk cannot become useful to the user and available to application programs until it is accessed by the computer's central processing unit. Hard drive interfaces provide a means of communication between these drives and the motherboard. Today there are many various types interfaces of hard drives, each of which has its own advantages, disadvantages and characteristic features. We hope that the information given in this article will be useful to the reader in many respects, because the choice of a modern hard drive is largely determined not only by its internal characteristics, such as capacity, cache memory, access and rotation speed, but also by the interface for which it was developed.
Hard drive for the server, features of choice
The hard drive is the most valuable component in any computer. After all, it stores information with which the computer and the user work, in the event that we are talking about personal computer. A person, each time sitting down at a computer, expects that the operating system loading screen will now run through, and he will start working with his data, which the hard drive will give out “on the mountain” from his bowels. If we are talking about a hard drive, or even an array of them as part of a server, then there are tens, hundreds and thousands of such users who expect to get access to personal or work data. And all their quiet work or recreation and entertainment depends on these devices that constantly store data in themselves. Already from this comparison it is clear that requests to hard drives home and industrial class are unequal - in the first case, one user works with it, in the second - thousands. It turns out that the second hard drive should be more reliable, faster, more stable than the first one many times over, because they work with it, many users rely on it. This article will discuss the types of hard drives used in the corporate sector and their design features to achieve the highest reliability and performance.
SAS and SATA drive and - so similar and so different
Until recently, the standards of industrial-grade and household hard drives differed significantly and were incompatible - SCSI and IDE, now the situation has changed - the overwhelming majority of hard drives are SATA and SAS (Serial Attached SCSI) on the market. The SAS connector is versatile and form factor compatible with SATA. This allows you to directly connect to the SAS system both high-speed, but at the same time small capacity (up to 300 GB at the time of writing) SAS drives, as well as slower, but many times more capacious SATA drives (up to 2 TB at the time of writing). ). Thus, in one disk subsystem, it is possible to combine vital important applications that require high performance and fast data access, and more cost-effective applications with a lower cost per gigabyte.
This interoperability benefits both backplate manufacturers and end users by reducing hardware and engineering costs.
That is, both SAS devices and SATA devices can be connected to SAS connectors, and only SATA devices can be connected to SATA connectors.
SAS and SATA high speed and large capacity. What to choose?
SAS disks, which replaced SCSI disks, completely inherited their main properties that characterize a hard drive: spindle speed (15000 rpm) and volume standards (36,74,147 and 300 GB). However, the SAS technology itself differs significantly from SCSI. Let's take a quick look at the main differences and features: The SAS interface uses a point-to-point connection - each device is connected to the controller by a dedicated channel, unlike it, SCSI works on a common bus.
SAS supports a large number of devices (> 16384), while the SCSI interface supports 8, 16, or 32 devices on the bus.
The SAS interface supports data transfer rates between devices at speeds of 1.5; 3; 6 Gb / s, while the SCSI interface bus speed is not allocated to each device, but is divided between them.
SAS supports the connection of slower SATA devices.
SAS configurations are much easier to assemble and install. Such a system is easier to scale. In addition, SAS hard drives inherited the reliability of SCSI hard drives.
When choosing a disk subsystem - SAS or SATA, you need to be guided by what functions will be performed by the server or workstation. To do this, you need to decide on the following questions:
1. How many simultaneous, diverse requests will the disk handle? If large - your clear choice - SAS disks. Also, if your system will serve a large number of users - choose SAS.
2. How much information will be stored on the disk subsystem of your server or workstation? If more than 1-1.5 TB, you should pay attention to a system based on SATA hard drives.
3. What is the budget allocated for the purchase of a server or workstation? It should be remembered that in addition to SAS disks, you will need a SAS controller, which also needs to be taken into account.
4. Do you plan, as a result, to increase the volume of data, increase productivity or increase the fault tolerance of the system? If so, then you need a SAS-based disk subsystem, it is easier to scale and more reliable.
5. Your server will run mission-critical data and applications - your choice is heavy-duty SAS drives.
A reliable disk subsystem, it is not only high-quality hard disks from a well-known manufacturer, but also an external disk controller. They will be discussed in one of the following articles. Consider SATA drives, what types of these drives are and which ones should be used when building server systems.
SATA drives: consumer and industrial sector
SATA drives used everywhere, from consumer electronics and home computers to high-performance workstations and servers, differ in subspecies, there are drives for use in household appliances, with low heat dissipation, power consumption, and as a result, low performance, there are drives - middle class, for home computers, and there are drives for high-performance systems. In this article, we will consider the class of hard drives for productive systems and servers.
Performance characteristics
|
Server class HDD |
HDD desktop class |
|
|
Rotational speed |
7,200 rpm (nominal) |
7,200 rpm (nominal) |
|
Cache size |
||
|
Average delay time |
4.20 ms (nominal) |
6.35 ms (nominal) |
|
Transfer rate |
||
|
Reading from drive cache (Serial ATA) |
maximum 3 Gb/s |
maximum 3 Gb/s |
|
physical characteristics |
||
|
Capacity after formatting |
1,000,204 MB |
1,000,204 MB |
|
Capacity |
||
|
Interface |
SATA 3 Gb/s |
SATA 3 Gb/s |
|
Number of sectors available to the user |
1 953 525 168 |
1 953 525 168 |
|
Dimensions |
||
|
Height |
25.4mm |
25.4mm |
|
Length |
147 mm |
147 mm |
|
Width |
101.6 mm |
101.6 mm |
|
0.69 kg |
0.69 kg |
|
|
impact resistance |
||
|
Shock resistance in working condition |
65G, 2ms |
30g; 2 ms |
|
Shock resistance when not in use |
250G, 2ms |
250G, 2ms |
|
Temperature |
||
|
In working order |
-0° C to 60° C |
-0° C to 50° C |
|
Out of Service |
-40° C to 70° C |
-40° C to 70° C |
|
Humidity |
||
|
In working order |
relative humidity 5-95% |
|
|
Out of Service |
relative humidity 5-95% |
relative humidity 5-95% |
|
Vibration |
||
|
In working order |
||
|
Linear |
20-300Hz, 0.75g (0 to peak) |
22-330Hz, 0.75g (0 to peak) |
|
Free |
0.004 g/Hz (10 - 300 Hz) |
0.005 g/Hz (10 - 300 Hz) |
|
Out of Service |
||
|
0.05 g/Hz (10 - 300 Hz) |
0.05 g/Hz (10 - 300 Hz) |
|
|
High frequency |
20-500Hz, 4.0G (0 to peak) |
The table shows the characteristics of hard drives from one of the leading manufacturers, one column shows the data SATA hard drive server class, in another conventional SATA hard drive.
From the table we can see that disks differ not only in performance characteristics, but also in operational characteristics, which directly affect the life expectancy and successful operation of the hard drive. You should pay attention to the fact that outwardly these hard drives differ insignificantly. Consider what technologies and features allow you to do this:
Reinforced shaft (spindle) of the hard disk, some manufacturers are fixed at both ends, which reduces the influence of external vibration and contributes to the precise positioning of the head unit during read and write operations.
The use of special intelligent technologies that take into account both linear and angular vibration, which reduces the positioning time of the heads and increases the performance of disks up to 60%
RAID runtime debugging feature - prevents hard drives from falling out of RAID, which is characteristic feature conventional hard drives.
The height adjustment of the heads in combination with the technology of preventing contact with the surface of the plates, which leads to a significant increase in the life of the disk.
A wide range of self-diagnostic functions that allow you to predict in advance the moment when the hard drive will fail and warn the user about it, which allows you to have time to save information to a backup drive.
Features that reduce the rate of unrecoverable read errors, which increases the reliability of the server hard drive compared to conventional hard drives.
Speaking about the practical side of the issue, we can confidently say that specialized hard drives in servers "behave" much better. The technical service receives many times fewer calls on the instability of the operation of RAID arrays and failures of hard drives. Support by the manufacturer of the server segment of hard drives is much faster than conventional hard drives, due to the fact that the industrial sector is a priority for any manufacturer of data storage systems. After all, it is in it that the most advanced technologies that guard your information are used.
Analogue of SAS disks:
Hard drives from Western Digital VelociRaptor. These 10K RPM drives are equipped with a SATA 6 Gb/s interface and 64 MB of cache. The MTBF of these drives is 1.4 million hours.
More details on the manufacturer's website www.wd.com
You can order a server assembly based on SAS or an analogue of SAS hard drives in our company "Status" in St. Petersburg, you can also buy or order SAS hard drives in St. Petersburg:
- call +7-812-385-55-66 in St. Petersburg
- write to the address
- Leave an application on our website on the page "Online application"
Little has changed over the past two years:
- Supermicro is ditching the proprietary "flipped" UIO form factor for controllers. Details will be below.
- LSI 2108 (SAS2 RAID with 512MB cache) and LSI 2008 (SAS2 HBA with optional RAID support) are still in service. Products based on these chips, both from LSI and from OEM partners, are well debugged and are still relevant.
- LSI 2208 appeared (the same SAS2 RAID with LSI MegaRAID stack, only with a dual-core processor and 1024MB of cache) and (an improved version of LSI 2008 with a faster processor and PCI-E 3.0 support).
Transition from UIO to WIO
As you remember, UIO boards are ordinary PCI-E x8 boards, in which the entire element base is located on the reverse side, i.e. when installed in the left riser, it is on top. This form factor was needed to install boards in the lowest slot of the server, which allowed four boards to be placed in the left riser. UIO is not only a form factor of expansion boards, it is also cases designed for installing risers, risers themselves and motherboards of a special form factor, with a cutout for the bottom expansion slot and slots for installing risers.This solution had two problems. Firstly, the non-standard form factor of expansion boards limited the choice of the client, since under the UIO form factor, there are only a few controllers SAS, InfiniBand and Ehternet. Secondly, there are not enough PCI-E lines in the slots for risers - only 36, of which there are only 24 lines for the left riser, which is clearly not enough for four boards with PCI-E x8.
What is WIO? At first it turned out that it was possible to place four boards in the left riser without having to "turn the sandwich butter up", and there were risers for regular boards (RSC-R2UU-A4E8+). Then the problem of the lack of lines (now there are 80) was solved by using slots with a higher pin density.
| UIO riser RSC-R2UU-UA3E8+ |
 |
| WIO riser RSC-R2UW-4E8 |
Results:
- WIO risers cannot be installed in UIO motherboards (eg X8DTU-F).
- UIO risers cannot be installed in new WIO boards.
- There are risers for WIO (on the motherboard) that have a UIO slot for cards. In case you still have UIO controllers. They are used in platforms under Socket B2 (6027B-URF, 1027B-URF, 6017B-URF).
- New controllers in the UIO form factor will not appear. For example, the USAS2LP-H8iR controller on the LSI 2108 chip will be the last one, there will be no LSI 2208 for UIO - only a regular MD2 with PCI-E x8.
PCI-E controllers
AT this moment three types are relevant: RAID controllers based on LSI 2108/2208 and HBA based on LSI 2308. There is also a mysterious SAS2 HBA AOC-SAS2LP-MV8 on the Marvel 9480 chip, but write about it because of its exoticism. Most use cases for internal SAS HBAs are storage with ZFS under FreeBSD and various flavors of Solaris. Due to the absence of problems with support in these operating systems, the choice in 100% of cases falls on LSI 2008/2308.LSI 2108
In addition to UIO "shny AOC-USAS2LP-H8iR, which is mentioned in two more controllers were added:
LSI 2108, SAS2 RAID 0/1/5/6/10/50/60, 512MB cache, 8 internal ports (2x SFF-8087). It is an analogue of the LSI 9260-8i controller, but manufactured by Supermicro, there are minor differences in the layout of the board, the price is $40-50 lower than LSI. All additional LSI options are supported: activation, FastPath and CacheCade 2.0, cache battery protection - LSIiBBU07 and LSIiBBU08 (now it is preferable to use BBU08, it has an extended temperature range and comes with a cable for remote mounting).
Despite the emergence of more powerful controllers based on the LSI 2208, the LSI 2108 is still relevant due to the price reduction. Performance with conventional HDDs is enough in any scenario, the IOPS limit for working with SSDs is 150,000, which is more than enough for most budget solutions.
LSI 2108, SAS2 RAID 0/1/5/6/10/50/60, 512MB cache, 4 internal + 4 external ports. It is an analogue of the LSI 9280-4i4e controller. Convenient for use in expander cases, as you don’t have to bring the output from the expander outside to connect additional JBODs, or in 1U cases for 4 disks, if necessary, provide the ability to increase the number of disks. Supports the same BBUs and activation keys.
LSI 2208
LSI 2208, SAS2 RAID 0/1/5/6/10/50/60, 1024MB cache, 8 internal ports (2 SFF-8087 connectors). It is an analogue of the LSI 9271-8i controller. LSI 2208 is a further development of LSI 2108. The processor became dual-core, which made it possible to raise the performance limit in terms of IOPS "m right up to 465000. Added PCI-E support 3.0 and increased to 1GB cache.
The controller supports BBU09 battery cache protection and CacheVault flash protection. Supermicro supplies them under part numbers BTR-0022L-LSI00279 and BTR-0024L-LSI00297, but it is easier to purchase from us through the LSI sales channel (the second part of the part numbers is the native LSI part numbers). MegaRAID Advanced Software Options activation keys are also supported, part number: AOC-SAS2-FSPT-ESW (FastPath) and AOCCHCD-PRO2-KEY (CacheCade Pro 2.0).
LSI 2308 (HBA)
LSI 2308, SAS2 HBA (with IR firmware - RAID 0/1/1E), 8 internal ports (2 SFF-8087 connectors). This is the same controller, it comes with different firmware. AOC-S2308L-L8e - IT firmware (pure HBA), AOC-S2308L-L8i - IR firmware (supporting RAID 0/1/1E). The difference is that L8i can work with IR and IT firmware, L8e can only work with IT, firmware in IR is locked. It is an analogue of the LSI 9207-8 controller i. Differences from LSI 2008: a faster chip (800 MHz, as a result - the IOPS limit has risen to 650 thousand), PCI-E 3.0 support has appeared. Application: software RAIDs (ZFS, for example), budget servers.
Based on this chip, there will be no cheap controllers supporting RAID-5 (iMR stack, out of ready-made controllers - LSI 9240).
Onboard controllers
In the latest products (X9 boards and platforms with them), Supermicro denotes the presence of a SAS2 controller from LSI with the number "7" in the part number, the number "3" indicates the chipset SAS (Intel C600). It just doesn't differentiate between the LSI 2208 and 2308, so be careful when choosing a board.- The LSI 2208-based controller soldered on motherboards has a maximum limit of 16 disks. If you add 17, it will simply not be detected, and you will see the message "PD is not supported" in the MSM log. Compensation for this is much more low price. For example, a bundle "X9DRHi-F + external controller LSI 9271-8i" will cost about $500 more than an X9DRH-7F with LSI 2008 on board. Bypassing this limitation by flashing in LSI 9271 will not work - flashing another SBR block, as in the case of LSI 2108, does not help.
- Another feature is the lack of support for CacheVault modules, there is simply not enough space on the boards for a special connector, so only BBU09 is supported. The ability to install the BBU09 depends on the enclosure used. For example, the LSI 2208 is used in the 7127R-S6 blade servers, there is a BBU connector, but to mount the module itself, you need an additional MCP-640-00068-0N Battery Holder Bracket.
- The SAS HBA (LSI 2308) firmware will now have to be done, since in DOS on any of the boards with LSI 2308 sas2flash.exe does not start with the error "Failed to initialize PAL".
Controllers in Twin and FatTwin platforms
Some 2U Twin 2 platforms come in three versions, with three types of controllers. For example:- 2027TR-HTRF+ - Chipset SATA
- 2027TR-H70RF+ - LSI 2008
- 2027TR-H71RF+ - LSI 2108
- 2027TR-H72RF+ - LSI 2208
| BPN-ADP-SAS2-H6IR (LSI 2108) |
 |
| BPN-ADP-S2208L-H6iR (LSI 2208) |
| BPN-ADP-SAS2-L6i (LSI 2008) |
Supermicro xxxBE16/xxxBE26 Enclosures
Another topic that is directly related to controllers is the modernization of cases with . Varieties have appeared with an additional basket for two 2.5" disks located on the rear panel of the case. The purpose is a dedicated disk (or mirror) for loading the system. Of course, the system can be loaded by selecting a small volume from another disk group or from additional disks fixed inside the case (in 846 cases, you can install additional fasteners for one 3.5" or two 2.5" drives), but the updated modifications are much more convenient:
Moreover, these additional disks do not need to be connected specifically to the chipset SATA controller. Using the SFF8087->4xSATA cable, you can connect to the main SAS controller through the expander's SAS output.
P.S. Hope the information was helpful. Don't forget that the most full information and technical support for products from Supermicro, LSI, Adaptec by PMC, and other vendors, contact True System.
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 dumb 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.
In modern computer systems SATA and SAS interfaces are used to connect the main hard drives. As a rule, the first option suits home workstations, the second - server ones, so the technologies do not compete with each other, meeting different requirements. The significant difference in cost and memory size makes users wonder how SAS differs from SATA and look for compromises. Let's see if this makes sense.
SAS(Serial Attached SCSI) is a serial interface for connecting storage devices, developed on the basis of parallel SCSI to execute the same set of commands. Used primarily in server systems.
SATA(Serial ATA) is a serial data exchange interface based on parallel PATA (IDE). It is used in home, office, multimedia PCs and laptops.
If we talk about the HDD, then, despite the differing specifications and connectors, there are no cardinal differences between the devices. Backward one-way compatibility makes it possible to connect disks to the server board both via one and the second interface.
It is worth noting that both connection options are also real for SSDs, but the significant difference between SAS and SATA in this case will be in the cost of the drive: the first can be dozens of times more expensive with a comparable volume. Therefore, today such a solution, if not rare, is sufficiently balanced, and is intended for fast corporate-level data centers.
Comparison
As we already know, SAS is used in servers, SATA - in home systems. In practice, this means that many users access the former at the same time and solve many tasks, while the latter is dealt with by one person. Accordingly, the server load is much higher, so the disks must be sufficiently fault-tolerant and fast. The SCSI protocols (SSP, SMP, STP) implemented in SAS allow you to process more I / O operations at the same time.
Directly for HDD speed circulation is determined primarily by the spindle speed. For desktop systems and laptops, 5400 - 7200 RPM is necessary and sufficient. Accordingly, it is almost impossible to find a SATA drive with 10,000 RPM (except to look at the WD VelociRaptor series, again designed for workstations), and anything higher is absolutely unattainable. SAS HDD spins at least 7200 RPM, 10000 RPM can be considered the standard, and 15000 RPM is a sufficient maximum.
Serial SCSI drives are considered to be more reliable and have higher MTBF. In practice, stability is achieved more due to the checksum verification function. SATA drives, on the other hand, suffer from “silent errors”, when data is partially written or corrupted, which leads to bad sectors.
The main advantage of SAS also works for the fault tolerance of the system - two duplex ports that allow you to connect one device via two channels. In this case, information exchange will be carried out simultaneously in both directions, and reliability is ensured by Multipath I / O technology (two controllers insure each other and share the load). The queue of tagged commands is built up to a depth of 256. Most SATA drives have one half-duplex port, and the queue depth using NCQ technology is no more than 32.
The SAS interface assumes the use of cables up to 10 m long. Up to 255 devices can be connected to one port through expanders. SATA is limited to 1m (2m for eSATA), and only supports point-to-point connection of one device.
Prospects for further development - what is the difference between SAS and SATA is also felt quite sharply. Bandwidth SAS interface reaches 12 Gb / s, and manufacturers announce support for data transfer rates of 24 Gb / s. The latest revision of SATA stopped at 6 Gb / s and will not evolve in this regard.
SATA drives in terms of the cost of 1 GB have a very attractive price tag. In systems where the speed of access to data is not critical, and the amount of stored information is large, it is advisable to use them.
Table
| SAS | SATA |
| For server systems | Primarily for desktop and mobile systems |
| Uses the SCSI command set | Uses the ATA command set |
| Minimum spindle speed HDD 7200 RPM, maximum - 15000 RPM | 5400 RPM minimum, 7200 RPM maximum |
| Supports checksum verification technology when writing data | A large percentage of errors and bad sectors |
| Two duplex ports | One half duplex port |
| Multipath I/O supported | Point-to-point connection |
| Command queue up to 256 | Command queue up to 32 |
| Cables up to 10 m can be used | Cable length no more than 1 m |
| Bus bandwidth up to 12 Gb/s (in the future - 24 Gb/s) | Bandwidth 6 Gbps (SATA III) |
| The cost of drives is higher, sometimes significantly | Cheaper in terms of price per 1 GB |