Hard disk (hard drive, HDD)- rewritable read-only memory (ROM) - the main storage medium in the computer. It stores data: both the operating system and user files (programs, games, movies, music, images ...). Hard disk memory is not volatile, which explains the ability to store data without supplying electricity to the device.
A hard drive is a set of one or more sealed disk-shaped plates coated with a layer of ferromagnetic material and reading heads in one housing. The plates are driven by a spindle (rotating shaft). The solenoid drive positions the head for data read/write operations.
Reading heads do not touch the surface of the disk both during data reading/writing (due to a layer of 5–10 nm free air flow, which is formed during very fast rotation), and during idle time of the disk (the heads are retracted to the spindle or outside the platters ). Due to the lack of contact, a hard drive can be overwritten an average of 100,000 times. Also, the duration of the disk is affected by a hermetic case (hermetic zone), thanks to which a space is created inside the HDD case, free from dust and moisture.
The main characteristics of the hard drive: interface, capacity, buffer size, physical size (form factor), random access time, data transfer rate, IOPS, spindle speed, noise level.
The first thing you should pay attention to when choosing a hard drive - interface- a device that converts and transmits signals between the HDD and the computer. The most common interfaces now are: SCSI, SAS, ATA (IDE, PATA), Serial ATA (SATA), eSATA and USB.
The SCSI interface has a speed of 640MB / s, it is used mainly on servers; SAS is its higher-speed counterpart (12 Gb / s), backwards compatible with the interface SATA.
ATA (IDE, PATA) - predecessor SATA, now it is no longer relevant due to its low speed of 150MB / s.
eSATA and USB - interfaces for external hard drives.
Serial ATA (SATA)- This is the most common hard drive interface. It is on him that you should be guided when choosing a hard drive. There are currently several variations SATA. From a physical point of view, they do not differ (the interfaces are compatible), the differences are only in speed: (SATA-I - 150 MB / s, SATA-II - 300 MB / s, SATA-III - 600 MB / s.).
As for the capacity: everything is simple. The larger it is, the better, as more information can be recorded. This characteristic does not affect the performance of the hard drive. Defined by the user based on the need for storage space for files. The table below shows the average sizes of the main file types that you should pay attention to when choosing HDD.
Buffer size (cache). Buffer (cache) is a volatile memory (similar to RAM) built into a hard disk, designed to smooth out differences in read / write speed, as well as store data that is accessed most often. The more cache, the better. The indicator varies from 8 to 64 MB. The most optimal value is 32 MB.
There are two main form factor for hard drives: 3.5 inches and 2.5 inches. The first is mainly used in desktop computers, the second - in laptops.
Random access time. This characteristic shows the average time during which the hard drive performs the operation of positioning the read / write head on an arbitrary section of the magnetic disk. The parameter ranges from 2.5 to 16 milliseconds. Naturally, the lower the value, the better.
Transfer rate. Modern hard drives have a speed of 50-75 Mb / s (for the inner zone of the HDD) and 65-115 Mb / s (for the outer zone).
The number of I/O operations per second. This characteristic ranges from 50 to 100 operations per second, depending on the placement of information on the disk.
The last three parameters should be considered in a hierarchical sequence, depending on the purpose of the hard drive. If you often use bulky applications, games, often watch movies in HD quality, they should be selected in the following sequence: data transfer rate > number of I / O operations per second > random access time. If you have a lot of small, frequently launched applications in your arsenal, then the hierarchy will look like this: random access time > number of IOPS > data transfer rate.
Spindle speed is the number of spindle revolutions per minute. Access time and average data transfer rate largely depend on this parameter. The most common are rotation speeds: 5400, 5900, 7200, 10000 and 15000 rpm. The optimal speed for a PC is 7200 rpm.
Noise level hard drive consists of spindle noise and positioning noise. Measured in decibels. This characteristic should be paid attention from the convictions of comfort.
RAID. If you have the funds to purchase two or more HDD you need to pay attention to the technology RAID (redundant array of independent disks)- an array of disks. This technology allows, on the one hand, to significantly increase the speed of data exchange with hard drives (similar to multichannel mode for RAM), on the other hand, to protect yourself from losing important data.
Outcome. First of all, you should think about the purpose of the disk, based on this, determine the volume, form factor. Based on the characteristics of your motherboard, choose an interface (most likely it will be SATA). Next, you should select disks with an acceptable buffer size, and determine the spindle speed. The parameters of the data transfer rate, the number of I / O operations per second, the random access time are selected according to the situation, depending on the need. We pay attention to the noise level if you need comfort.
Choosing a hard drive for a PC is a very responsible task. After all, it is the main repository of both official and your personal information. In this article, we will talk about the key characteristics of the HDD, which you should pay attention to when buying a magnetic drive.
Introduction
When buying a computer, many users often focus on the characteristics of its components such as monitor, processor, video card. And such an integral component of any PC as a hard drive (in computer slang - a hard drive), buyers often purchase, guided only by its volume, practically neglecting other important parameters. Nevertheless, it should be remembered that a competent approach to choosing a hard drive is one of the guarantees of comfort during further work at the computer, as well as financial savings, in which we are so often constrained.
A hard disk drive or hard disk drive (HDD) is the main storage device in most modern computers, which stores not only the information needed by the user, including movies, games, photos, music, but also the operating system, as well as everything installed programs. Therefore, in fact, the choice of a hard drive for a computer should be treated with due attention. Remember that if any element of the PC fails, it can be replaced. The only negative point in this situation is the additional financial costs for repairs or the purchase of a new part. But a hard drive failure, in addition to unforeseen costs, can lead to the loss of all your information, as well as the need to reinstall the operating system and all required programs. The main purpose of this article is to help novice PC users in choosing a hard drive model that would best meet the requirements of specific "users" for a computer.
First of all, you should clearly decide in which computer device the hard drive will be installed and for what purposes this device is planned to be used. Based on the most common tasks, we can conditionally divide them into several groups:
- A mobile computer for general tasks (working with documents, "surfing" the expanses of the World Wide Web, data processing and working with programs).
- Powerful mobile computer for gaming and resource-intensive tasks.
- Desktop computer for office tasks;
- A productive desktop computer (working with multimedia, games, audio, video and image processing);
- Multimedia player and data storage.
- To assemble an external (portable) drive.
In accordance with one of the listed options for operating a computer, you can begin to select a suitable hard drive model according to its characteristics.
Form factor
Form factor is the physical size of a hard drive. Today, most drives for home computers are 2.5 or 3.5 inches wide. The first, which are smaller, are designed for installation in laptops, the second - in stationary system units. Of course, if desired, a 2.5-inch drive can also be installed in a desktop PC.
There are also smaller magnetic drives with sizes of 1.8", 1" and even 0.85". But these hard drives are much less common and are focused on specific devices, such as ultra-compact computers (UMPC), digital cameras, PDAs and other equipment, where small dimensions and weight of components are very important. We will not talk about them in this article.
The smaller the drive, the lighter it is and the less power it needs to run. Therefore, 2.5" form factor hard drives have almost completely replaced 3.5" models in external drives. Indeed, for the operation of large external drives, additional power is required from an electrical outlet, while the younger brother is content only with power from USB ports. So if you decide to assemble a portable drive yourself, then it is better to use a 2.5-inch HDD for this purpose. It will be a lighter and more compact solution, and you won’t have to carry a power supply with you.
As for the installation of 2.5-inch drives in a stationary system unit, such a decision looks ambiguous. Why? Read on.
Capacity
One of the main characteristics of any drive (in this regard, a hard drive is no exception) is its capacity (or volume), which today in some models reaches four terabytes (1024 GB in one terabyte). Some 5 years ago, such a volume might have seemed fantastic, but current OS builds, modern software, high-resolution video and photos, as well as three-dimensional computer video games, having a fairly solid “weight”, need a large hard drive capacity. So, some modern games need 12 or even more gigabytes of free hard disk space for normal functioning, and an hour and a half HD-quality movie may require more than 20 GB for storage.
To date, the capacity of 2.5-inch magnetic media ranges from 160 GB to 1.5 TB (the most common volumes are 250 GB, 320 GB, 500 GB, 750 GB and 1 TB). 3.5" drives for desktops are more capacious and can store from 160GB to 4TB of data (the most common sizes are 320GB, 500GB, 1TB, 2TB and 3TB).
When choosing a HDD capacity, consider one important detail - the larger the hard drive capacity, the lower the price of 1 GB of information storage. For example, a desktop hard drive for 320 GB costs 1600 rubles, for 500 GB - 1650 rubles, and for 1 TB - 1950 rubles. We consider: in the first case, the cost of a gigabyte of data storage is 5 rubles (1600 / 320 = 5), in the second - 3.3 rubles, and in the third - 1.95 rubles. Of course, such statistics do not mean that it is necessary to buy a very large disk, but in this example it is very clear that buying a 320-gigabyte disk is not advisable.
If you plan to use your computer mainly for office tasks, then a hard drive with a capacity of 250 - 320 GB, or even less, will be more than enough for you, unless, of course, there is a need to store huge archives of documentation on the computer. At the same time, as we noted above, buying a hard drive with a capacity of less than 500 GB is unprofitable. Having saved from 50 to 200 rubles, in the end you get a very high cost per gigabyte of data storage. At the same time, this fact applies to disks of both form factors.
Do you want to build a gaming or multimedia PC to work with graphics and video, plan to download new movies and music albums to your hard drive in large quantities? Then it is better to choose a hard drive with a capacity of at least 1 TB for a desktop PC and at least 750 GB for a mobile one. But, of course, the final calculation of the hard drive capacity must meet the specific needs of the user, and in this case we only give recommendations.
Separately, it is worth noting systems for data storage (NAS) and multimedia players that have become popular. As a rule, large 3.5” disks are installed in such equipment, preferably with a capacity of at least 2 TB. After all, these devices are focused on storing large amounts of data, which means that the hard drives installed in them must be capacious with the lowest price for storing 1 GB of information.
Disc geometry, platters and recording density
When choosing a hard disk, you should not blindly focus only on its total capacity, according to the principle “the more, the better.” There are other important characteristics, including: recording density and the number of platters used. After all, not only the volume of the hard drive, but also the speed of writing / reading data directly depends on these factors.
Let's make a small digression and say a few words about the design features of modern hard disk drives. Data is recorded in them on aluminum or glass disks, called plates, which are covered with a ferromagnetic film. For writing and reading data from one of the thousands of concentric tracks located on the surface of the plates, read heads are responsible, located on special rotary positioner brackets, sometimes called "rocker arms". This procedure occurs without direct (mechanical) contact between the disc and the head (they are at a distance of about 7-10 nm from each other), which provides protection against possible damage and a long service life of the device. Each plate has two working surfaces and is served by two heads (one for each side).
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To create an address space, the surface of magnetic disks is divided into many circular areas called tracks. In turn, the tracks are divided into equal segments - sectors. Due to such a ring structure, the geometry of the plates, or rather their diameter, affects the speed of reading and writing information.
Closer to the outer edge of the disk, the tracks have a larger radius (greater length) and contain more sectors, and hence more information that can be read by the device in one revolution. Therefore, on the outer tracks of the disk, the data transfer rate is higher, since the reading head in this area overcomes a greater distance in a certain time period than on the inner tracks, which are closer to the center. Thus, disks with a diameter of 3.5 inches perform better than disks with a diameter of 2.5 inches.
Several platters can be located inside a hard disk at once, each of which can record a certain maximum amount of data. Strictly speaking, this determines the density of the recording, measured in gigabits per square inch (Gb / inch 2) or in gigabytes per platter (GB). The larger this value, the more information is placed on one track of the plate, and the faster the recording is carried out, as well as the subsequent reading of information arrays (regardless of what the disk rotation speed is).
The total volume of the hard drive is the sum of the capacities of each of the plates placed in it. For example, appeared in 2007, the first commercial drive with a capacity of 1000 GB (1TB) had as many as 5 platters with a density of 200 GB each. But technological progress does not stand still, and in 2011, thanks to the improvement of perpendicular recording technology, Hitachi introduced the first 1TB platter, which is ubiquitous in today's large-capacity hard drives.
Reducing the number of platters in hard drives has a number of important benefits:
- Decrease in data reading time;
- Reducing energy consumption and heat generation;
- Increasing reliability and fault tolerance;
- Reducing weight and thickness;
- Cost reduction.
To date, the computer market at the same time there are models of hard drives that use plates with different recording densities. This means that hard drives of the same volume can have a completely different number of platters. If you are looking for the most efficient solution, then it is better to choose an HDD with the least number of magnetic platters and high recording density. But the problem is that, in almost no computer store, in the descriptions of the characteristics of disks, you will not find the value of the above parameters. Moreover, this information is often missing even on the official websites of manufacturers. As a result, for ordinary ordinary users, these characteristics are not always decisive when choosing a hard drive, due to their inaccessibility. Nevertheless, before buying, we recommend that you definitely find out the values of these parameters, which will allow you to choose a hard drive with the most advanced and modern characteristics.
Spindle speed
The performance of a hard disk directly depends not only on the recording density, but also on the rotation speed of the magnetic disks placed in it. All plates inside the hard drive are rigidly attached to its internal axis, called the spindle, and rotate with it as a whole. The faster the plate rotates, the sooner there will be a sector that should be read.
In stationary home computers, hard drive models with an operating speed of 5400, 5900, 7200, or 10,000 rpm are used. Units with a 5400 rpm spindle speed are generally quieter than their high-speed competitors and generate less heat. Hard drives with higher speeds, in turn, have better performance, but at the same time are more energy-intensive.
For a typical office PC, a drive with a spindle speed of 5400 rpm will suffice. Also, such discs are well suited for installation in multimedia players or data storage, where an important role is played not so much by the speed of information transfer as by reduced power consumption and heat dissipation.
In other cases, in the vast majority, discs with a plate rotation speed of 7200 rpm are used. This applies to both mid-range and high-end computers. The use of HDD with a rotation speed of 10,000 rpm is relatively rare, since such models of hard drives are very noisy and have a rather high cost of storing one gigabyte of information. Moreover, in recent years, users are increasingly preferring to use solid-state drives instead of high-performance magnetic disks.
In the mobile sector, where 2.5-inch drives reign, the most common spindle speed is 5400 rpm. This is not surprising, since low power consumption and a low level of heating of parts are important for portable devices. But we didn't forget about the owners of productive laptops - there is a large selection of models with a rotation speed of 7200 rpm on the market, and even several members of the VelociRaptor family with a rotation speed of 10,000 rpm. Although the expediency of using the latter even in the most powerful mobile PCs is in great doubt. In our opinion, if you need to install a very fast disk subsystem, it is better to pay attention to solid state drives.
Connection interface
Almost all modern models, both small and large hard drives, are connected to personal computer motherboards using the SATA (Serial ATA) serial interface. If you have a very old computer, then you can connect using a parallel PATA (IDE) interface. But keep in mind that the assortment of such hard drives in stores today is very scarce, since their production has almost completely ceased.
As for the SATA interface, there are 2 disk options on the market: connection via the SATA II or SATA III bus. In the first option, the maximum data transfer rate between the disk and RAM can be 300 MB / s (bus bandwidth up to 3 Gb / s), and in the second - 600 MB / s (bus bandwidth up to 6 Gb / s). The SATA III interface also has slightly improved power management.
In practice, for any classic hard drives, the bandwidth of the SATA II interface is enough for the eyes. Indeed, even in the most productive HDD models, the speed of reading data from platters barely exceeds 200 MB / s. Another thing is solid-state drives, where data is stored not on magnetic platters, but in flash memory, the reading speed from which is many times higher and can reach values of over 500 MB / s.
It should be noted that all versions of the SATA interface maintain compatibility with each other at the level of exchange protocols, connectors and cables. That is, a hard drive with a SATA III interface can be easily connected to the motherboard via a SATA I connector, although the maximum disk throughput will be limited by the capabilities of an older revision and will be 150 MB / s.
Buffer Memory (Cache)
Buffer memory is a fast intermediate memory (usually a standard type of RAM) that is used to level (smooth out) the difference between the speeds of reading, writing and transferring data over the interface during disk operation. The hard drive cache can be used to store the last data read, but not yet transferred for processing, or those data that can be requested again.
In the previous section, we already noted the difference between hard drive performance and interface bandwidth. It is this fact that determines the need for transit storage in modern hard drives. Thus, while data is being written to or read from magnetic platters, the system can use the information stored in the cache for its own needs without waiting.
The size of the clipboard for modern hard drives made in the 2.5 ”form factor can be 8, 16, 32 or 64 MB. The older 3.5-inch brothers have a maximum buffer memory value of 128 MB. In the mobile sector, disks with 8 and 16 MB cache are the most common. Among hard drives for desktop PCs, the most common buffer sizes are 32 and 64 MB.
In theory, a larger cache should provide better performance to the disks. But in practice this is not always the case. There are various disk operations in which the clipboard practically does not affect the performance of the hard drive. For example, this can happen when sequentially reading data from the surface of the plates or when working with large files. In addition, the efficiency of the cache is affected by algorithms that can prevent errors when working with the buffer. And here, a disk with a smaller cache, but with advanced algorithms for its operation, may turn out to be more productive than a competitor with a larger clipboard.
Thus, chasing the maximum amount of buffer memory is not worth it. Especially if you need to significantly overpay for a large cache capacity. In addition, manufacturers themselves try to equip their products with the most efficient cache size, based on the class and characteristics of certain disk models.
Other characteristics
In conclusion, let's take a quick look at some of the remaining characteristics that you may come across in hard drive descriptions.
Reliability or mean time between failures ( MTBF) - the average duration of the hard drive before its first breakdown or the need for repair. It is usually measured in hours. This parameter is very important for disks used in server stations or file storages, as well as in RAID arrays. As a rule, specialized magnetic drives have an average operating time of 800,000 to 1,000,000 hours (for example, WD's RED series or Seagate's Constellation series).
Noise level - the noise generated by the elements of the hard drive during its operation. Measured in decibels (dB). It mainly consists of the noise that occurs during the positioning of the heads (crackling) and the noise from the rotation of the spindle (rustling). As a rule, the lower the spindle speed, the quieter the hard drive works. A hard drive can be called quiet if its noise level is below 26 dB.
Power consumption - an important parameter for drives installed in mobile devices, where a long battery life is valued. Also, the heat dissipation of the hard drive directly depends on the energy consumption, which is also important for portable PCs. As a rule, the level of energy consumption is indicated by the manufacturer on the cover of the disc, but you should not blindly trust these figures. Very often they are far from reality, so if you really want to find out the power consumption of a particular drive model, then it is better to search the Internet for independent test results.
Random access time - the average time for which the positioning of the disk reading head over an arbitrary section of the magnetic plate is performed, measured in milliseconds. A very important parameter that affects the performance of the hard drive as a whole. The shorter the positioning time, the faster the data will be written to or read from the disk. It can be from 2.5 ms (for some server disk models) to 14 ms. On average, for modern disks for personal computers, this parameter ranges from 7 to 11 ms. Although there are also very fast models, for example, WD Velociraptor with an average random access time of 3.6 ms.
Conclusion
In conclusion, I would like to say a few words about the increasingly popular hybrid magnetic drives (SSHD). Devices of this type combine a conventional hard disk drive (HDD) and a small solid state drive (SSD) that acts as an additional cache memory. Thus, developers are trying to use together the main advantages of the two technologies - the large capacity of magnetic plates and the speed of flash memory. At the same time, the cost of hybrid drives is much lower than that of newfangled SSDs, and slightly higher than conventional HDDs.
Despite the promise of this technology, so far SSHD drives on the hard drive market are very poorly represented by only a small number of models in the 2.5-inch form factor. Seagate is the most active in this segment, although competitors Western Digital (WD) and Toshiba have also already presented their hybrid solutions. All this leaves hope that the market for SSHD hard drives will develop, and in the near future we will see new models of such devices on sale not only for mobile computers, but also for desktop PCs.
This concludes our review, where we looked at all the main characteristics of computer hard drives. We hope that based on this material, you will be able to choose a hard drive for any purpose with the appropriate optimal parameters.
It is known that hard drives are equipped with their own buffer memory of a relatively small amount. The buffer is used as a built-in cache for read and write operations, optimizing performance and minimizing time-consuming platter accesses. For example, when there is free space in the buffer, the controller can temporarily place data that needs to be written there and wait for a convenient moment when there are no requests from the system (host). When making read requests, the controller stores the last read data in case the host requests it again - then there is no need to access the disk again. The controller often reads ahead in an attempt to predict the host's next requests, and buffers the data it reads as well. It turns out that the buffer is used by the hard disk all the time, and its role is very important.
Hard drive manufacturers have always sought to increase the amount of buffer memory. Today, this is easier to do, since conventional synchronous dynamic memory (SDRAM) chips, and they are used in hard drives, are quite inexpensive. In the late 90s, desktop hard drives were equipped with a 512 KB buffer, then most models received 2 MB of memory, and today hard drives with an 8 MB buffer are most common. However, there is no limit to perfection: WD has updated its mass-produced line of Caviar SE hard drives, supplementing it with Caviar SE16 models. Their main difference, as you may have guessed, is the doubled amount of buffer memory.
Why do we need 16 MB?
It would seem that the larger the amount of buffer memory, the higher the performance of the hard disk. The controller will be able to buffer more data, which means it will access magnetic platters less often. However, not everything is as simple as it seems at first glance.
Caching algorithms typically use an associative lookup technique to determine if the required data is in the buffer. To increase the amount of data stored in the cache, either increase the size of one block (cache line) or increase the number of lines. And this is fraught with the appearance of additional problems with associative search and data exchange with the cache.
However, for a hard drive, the caching speed is not so important, since in any case it is negligible compared to the delays when accessing a magnetic media. Another thing is whether the controller really needs additional memory. It is possible that the hard drive is not busy enough to fully utilize the available buffer capacity. For example, when simply copying and downloading programs, nothing needs to be cached, since the data is read only once. But when working in a server environment, when requests are received chaotically and continuously, a large buffer is a significant plus for a hard drive. Actually, that's why server hard drives were always equipped with a buffer of at least 8 MB. But on a desktop, read and access speed is more important than buffering efficiency.
(True, let's not forget about NCQ technology. With its help, the hard drive can manage the queue of requests, changing the order of their service. Since in this case the nature of access to the media also changes, additional buffering can help improve performance. But alas, most users still still does not know how NCQ can be used, since support from the hard drive alone is not enough here).
It turns out that a large buffer size is unlikely to have a significant impact on the overall speed. Putting a chip with a higher capacity is not enough to improve performance. Developers should not only redesign the microcode, but also improve the read / write speed of the media and the bandwidth of the interface.
Caviar SE16. Design features
We were able to match the WD2500KS from the Caviar SE16 line with the WD2000JS from the "standard" Caviar SE line. As it turned out, they have a minimum of differences: the markings of the HDA, connectors, and electronics boards are the same. Even the microcode version is the same. Consequently, the developers at WD used the old technology, simply replacing one memory chip with another.
For those who are not aware of the features of WD hard drives, we will report the following. This manufacturer uses only proven technologies and takes special care to protect discs from damage. The design of the HDA is standard: a massive body and a flat top cover are hermetically connected, and there is an air vent on the top of the cover. But the electronics board is traditionally turned upside down by microcircuits and pressed against the case, there is a thermally conductive gasket. This technique allows you to protect the chips from overheating and external influences. There are two power connectors - a standard 4-pin and a new flat one, in accordance with the requirements of Serial ATA. To protect the Serial ATA interface connector from accidental disconnection, WD suggests using a special SecureConnect cable with latches.
The Caviar SE16 series is only available with Serial ATA support. Moreover, the hard disk controller supports the "second speed" 3 GB/s (300 MB/s). Other technologies, in particular, NCQ, have not yet been implemented - here WD lags behind other manufacturers.
Declared parameters of WD Caviar SE/SE16 hard drives |
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Marking |
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Spindle speed, rpm |
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Recording density, GB per platter |
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Cache buffer size, MB |
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Bearings |
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Interface |
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NCQ Support |
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Capacity range |
120, 160, 200, 250 |
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Int. data exchange speed, Mbit/s |
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Average access speed: average, ms |
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- by maximum radius, ms |
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- transition between tracks, ms |
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-write access speed, ms |
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Impact resistance (offline), G |
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Impact resistance (online), G |
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Noise level at idle, dB |
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Noise level during positioning, dB |
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Testing
Hard drives from three manufacturers took part in testing - WD, Seagate and Samsung. At the time of writing, it was their products that were presented in a wide range. An instance of the Caviar SE16 series hard drive considered in the review had the following parameters:
- marking WD2500KS-00MJB0;
- volume 250 GB;
- microcode version 02.01C03;
- quiet positioning mode (AAM) disabled (0FEh).
We will compare the following hard drives with it:
- Caviar SE, from the line with 8 MB buffer, 200 GB capacity:
- marking: WD2000JS-00MHB0;
- buffer size - 8 MB;
- interface - Serial ATA 3 Gbit/s, NCQ is not supported;
- microcode version - 02.01C03 (same);
- quiet positioning mode (AAM) disabled (0FEh).
- Samsung SpinPoint P120, 200 GB:
- marking SP2004C;
- buffer size - 8 MB;
- interface – Serial ATA 3 Gbit/s, NCQ supported;
- microcode version - VM100-33;
- silent positioning mode enabled (code 00h).
- Seagate Barracuda 7200.8, 200 GB:
- marking ST3200826AS;
- buffer size - 8 MB;
- interface – Serial ATA 1.5 Gbit/s, NCQ supported;
- microcode version - 3.03;
- silent positioning mode disabled (control not available).
Seagate and Samsung hard drives have higher storage density than WD Caviar. In addition, Seagate has a higher positioning speed (8ms versus 8.9ms for Samsung and WD), and Samsung is quieter. That is, WD formally has no advantages over drives from other manufacturers. But in practice it can be the other way around.
The hard drives were connected to the second port of the Serial ATA controller built into the ICH5 south hub of the Intel 865G chipset. Unfortunately, the 865 series chipsets do not support 3 Gb/s and NCQ technology, so the capabilities of modern hard drives cannot be fully revealed. Other test configuration options:
- host hard drive from which the OS was loaded and tests were launched - Seagate Barracuda 7200.7 PATA 80 GB;
- processor Intel Pentium 4 2.80 (bus 800 MHz);
- motherboard Intel D865GBF (Intel 865G);
- 2 x 256 DDR400 memory, dual-channel enabled;
- video card GeForce FX 5600;
- the hard drives were installed in a 2.5-inch basket of the Inwin J551 case, no special cooling was used.
Low Level Tests
The use of programs that work directly with the disk allows you to measure the theoretical parameters of the hard drive - the speed of random access, the average (sustained) speed of reading and writing, the efficiency of delayed writing. At the same time, the influence of caching algorithms is minimal, since access is carried out continuously and according to a simple scheme.
Low-level parameters were calculated using programs:
- IOMeter 2004.07.30;
- HDTach 2.68;
- HDTach 3.0.1.0;
- Winbench 2.0 (the disk was formatted as one large NTFS partition).
Access speed turned out to be higher in Caviar, since WD hard drives do not use positioning delay algorithms (AAM). Seagate, despite the excellent declared numbers, was the last one. Oddly enough, the Caviar SE16 slightly (0.3 ms) lost to its counterpart, which can be explained either by the natural difference in technological parameters (nevertheless, the mechanics have some deviations in one direction or another), or by the influence of the third plate (the greater the number of heads, the more switching delay). Of course, the differences are actually very small, and we will not talk about a serious lag in the Caviar SE16. In terms of write access speed, WD hard drives are equal, providing a twofold acceleration compared to the read access speed. This is explained by the influence of the delayed write algorithm.
By sequential read/write speeds The Caviar SE16, on the other hand, is slightly ahead of the Caviar SE. But they were overtaken by the Seagate hard drive (+10%), which is natural due to the use of a higher recording density, while Samsung, on the contrary, is just as far behind.
A more accurate analysis of the read / write speed allows you to conduct IOMeter. If other programs work with 64 KB blocks, IOMeter may vary the block size.
Seagate is the leader in reading: it copes much better (+20%) with small and large blocks. Samsung, as it turned out, does not work very well with small blocks. And WD performed well in write tests, beating Seagate when working with blocks less than 64 KB.
The Winbench'99 program, despite its venerable age, builds a sequential reading graph quite accurately.
Both WD drives have the same shape of the graph, with no peaks or dips, which indicates a high read stability. The Caviar SE16 graph is more elongated, which is due to its larger capacity. Zooming in on the graph allows you to see short-term but strong speed dips in Seagate and Samsung (work of ECC error correction algorithms, delays in switching heads and changing tracks) and the absence of such in WD. And although the recording density of WD is worse, the proven production technology has its advantages - higher stability.
Application Simulation
The Workstation template of the IOMeter test allows you to generate a load on the disk subsystem that is close to real (statistics were collected using the Winstone 2002 Content Creation test). So, this test is more sensitive to access speed than to read / write speed, plus it takes into account the work of caching algorithms, since requests arrive with an increase in the queue depth.
According to the data, both WD drives slightly outperformed Samsung and literally crushed Seagate. Caviar SE is again slightly better than Caviar SE16, as they have a slight difference in access speed.
We pinned great hopes on the PCMark05 test, since it should show the advantage of a large cache buffer. This test uses patterns written with the Intel IPEAK SPT test suite when performing specific tasks. Therefore, PCMark05 can more or less believably simulate the operation of a hard drive in real conditions.
So, if WD hard drives almost do not differ in the speed of loading Windows XP, copying files and scanning for viruses, then in terms of application loading speed and access to data while applications are running, Caviar SE16 is 10-15% faster than Caviar SE, not to mention Samsung and Seagate.
The advantage of a hard drive with a large buffer is also noticeable in the Winstone test, especially if the FAT32 file system is used.
conclusions
The test results prove that there is a positive effect of increasing the buffer. It is small, within 10-15%, and appears only when the hard drive is operating in conditions close to real. In low-level tests, there is practically no difference, which is consistent with the theory. The same theory suggests that as the interface bandwidth and recording density increase, as well as with the introduction of disk access optimization technologies, the buffer size will have to be increased. Therefore, the developers from WD hurried a little; however, it is better to start developing the technology now than to catch up with competitors later.
The question of upgrading a computer sooner or later arises before each user. Maybe you're building a new PC, or you want to store more information on your machine and use it effectively. To do this, you can not do without buying a new high-quality HDD (hard disc drive). In each case, you need to have a clear understanding of how to choose a good hard drive that will meet all your needs and be reliable in operation.
In each case, you need to have a clear understanding of how to choose a good hard drive that will meet all your needs and be reliable in operation.
At the first stage, you need to decide for what purpose you plan to use the data drive. Depending on the application, there are different price categories for hdd. Manufacturers produce a series of products designed primarily for: Archival function (data storage); Daily work (regular writing and reading information);
Active work with a large amount of data, where increased reliability is needed - such solutions serve the corporate sector.
physical dimensions hdd
Two form factors have been developed that determine the physical dimensions of hard drives. Smaller drives are used in portable PC models, while larger ones are designed for a desktop computer. There are the following options: 2.5 '' (inches) - for laptops of any configuration, in order to connect such a drive to a stationary machine, special mounts for the case will be required;
3.5'' (inches) - for personal workstations, is considered the "gold standard" for desktop computers.
Hard disk interface
Before buying, you must definitely find out with the help of which interface the new drive will be connected to the motherboard. A mismatch between the interfaces on the board and the hdd leads to the complete impossibility of using it or can significantly reduce the speed of work.
Older models used an IDE (or Parallel ATA) interface, which involves connecting the device in parallel to a computer. In recent years, it has been replaced by the more modern and faster SATA (Serial ATA) interface, which is used to serially connect hard drives to the motherboard and offers better read and write data compared to its predecessor.
There are three generations of SATA interfaces: SATA I, which transfers data at a speed of 1.5 Gb per second, is also becoming a thing of the past; SATA II, which transfers data at speeds up to 3 Gbps;
SATA III, the fastest interface with a transfer rate of about 6 Gbps;
Note that desktop and mobile machines using the IDE connector are not compatible with each other, therefore, if it becomes necessary to connect a hard drive from a laptop to a PC or vice versa, a special adapter is required.
The SATA II and SATA III connectors are designed to completely solve this problem. They are fully compatible, but be aware that when you connect a SATA III hard drive to a SATA II equipped motherboard, it will run slower and have the same performance as the second generation interfaces.
If you are thinking about how to choose a hard drive for your computer, then it is desirable that the model you choose has an interface of the second or third generation (SATA II, SATA III).
Capacity or volume hdd
When choosing the size of the drive, proceed from your needs and the tasks that the computer where you plan to connect the device will perform.
If you are choosing a new hard drive for a desktop computer, then you should be guided by the following numbers: Volume 320 GB, if the machine is needed in order to use text editors and browse the web; Volume from 500 GB to 1 TB, if, in addition to the most common programs, multimedia files (music, photos, movies) are stored on the disk and modern games are planned to be installed;
A volume of 2 to 4 TB will be needed for a PC on which professional processing of graphic files and video clips will be carried out, as well as storage and processing of large amounts of information.
Installing an hdd with a capacity of more than 2 GB is not possible on machines that do not support the UEFI standard, which is gradually replacing motherboards with BIOS. Therefore, if you have chosen a hard drive with a very large capacity, make sure that your computer belongs to the required PC class. The BIOS will not be able to identify and work correctly in the future with such a device.
When buying a new hard drive for a laptop, be guided by the following data: From 320 to 500 GB if you have a netbook, which is used as an additional car when traveling outside the home;
From 750 GB to 1 TB, if you use a laptop as a base workstation and, in addition to the installed operating system, you need to store a large amount of information and work with complex software.
If you need to pick up an hdd, keep in mind that you need to have additional space on it for backup copies of files. This will increase the reliability of the drive and reduce the chance of sudden loss of valuable data. In some cases, the best solution would be if you choose several drives for a special information duplication system.
Optimum hard drive speed
The main principle of the hard drive is the rotation of the disk platters around its axis, during which the magnetic head reads and writes data. The number of revolutions depends on the spindle speed. In proportion to the increase in this parameter, the intensity of information exchange with the system and the speed of the disk increase.
There are several types of disks based on the values of this indicator: Models operating at a speed of 5400 rpm - are used mainly in laptops (you can choose for a desktop PC for archival purposes), they have low power consumption, do not make noise, but work quite slowly; Drives with a speed of 7200 rpm - the most popular hard drives have such characteristics, as they are optimal for solving most of the tasks that users face;
Devices with a speed of 10,000 to 15,000 rpm are very fast and productive, used in the corporate sector, designed for powerful servers (they are rarely chosen for home use in case of non-standard needs);
Buffer memory (cache) size for hdd
Everyone who collects information on how to choose a hard drive for a PC should pay attention to the cache size of this device. It stores data that has been extracted from the media, but not yet loaded into RAM, and those that came from other system components and have not yet been written to the hdd. Too little buffer memory can slow down the disk.
On the modern market there are devices whose cache size ranges from 16 to 64 MB. A good hard drive should have a 32 MB or 64 MB buffer to keep it running efficiently. It is usually recommended to choose a hard drive with a large amount of cache.
Options for reading and writing information
The main parameters that determine how productively the device will exchange data with the rest of the computer are the linear read and write speeds of data, as well as the random access time.
The speed of the device is directly determined by the speed of linear reading, which should be remembered by every potential buyer who is thinking about which hard drive to choose for the system. The value of this characteristic, which lies in the range from 120 to 140 Mb / s, is considered optimal. You should not purchase a model that has a linear read speed below 100 MB per second.
The second important indicator of device performance is the random access time. It especially affects the time with which the head reads small files from the disk. For a high-quality hard drive, this figure is no more than 14 ms. Operational problems arise with devices whose random access time reaches 16-19 ms.
Be vigilant, because these indicators are not indicated by the manufacturer on the packaging of the device and they cannot be found on the websites of online stores. They are determined using special software (for example, HD Tune 2.5) only on a working drive. Therefore, one of the instructions on how to choose a good hard drive is to search and study in detail the reviews and tests of the hdd model you like. It is from them that you can find out the real numbers and independently correctly evaluate before purchasing how this or that hard drive behaves in practice.
Top Hard Drive Manufacturers
There are several leaders in the hdd manufacturer market, which guarantee the high quality of their products, their reliability and durability. Before buying a hard drive, be sure to check the reputation of its manufacturer, as purchasing a model from an unknown company may cause data loss on your PC in the future.
Important information for those who want to know how to choose the right hard drive for your computer is that quality models are offered primarily by Seagate and Western Digital (WD) corporations. Also in specialized stores you can find devices from Hitachi and Samsung, but their percentage of the total number of devices offered is not too large.
Manufacturers launch various series of models on the market, which are aimed at private and corporate customers, which causes differences in price, volume and technical characteristics of products.
For example, Western Digital uses a simple color coding of its products, which can be used to correctly understand the specifics of using a particular device.
Hard drives with a blue mark on the case (Cover Blue) are budget solutions that have good performance parameters, but they should not be used to store especially important information.
Drives that have a green mark (Cover Green) are models that require little electricity to operate, they have average performance and produce little noise.
Devices with a red case marking (Cover Red) - disks with high speed and high performance, equipped with the most modern control controllers.
HDDs with a black marking on the case (Cover Black) contain the best features of the models with a red marking and guarantee very high reliability of data storage.
Thanks to this detailed instruction, purchasing a good hard drive for your PC will not cause you any difficulties, because we talk about computers in Russian and make information available to every user. Following this algorithm will allow you to choose exactly the hdd that will become a reliable component of your machine and help in solving all current problems.
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Form factor, buffer size and other HDD characteristics
In previous articles that dealt with the characteristics of the HDD, such parameters as the speed of rotation of the spindle and the noise level emitted by the hard drive were touched upon in some detail.
Also, they did not bypass the HDD interface, where the main features and differences between the SATA interface and the outdated IDE were considered. And of course, they did not forget, perhaps, the most important characteristic - this is the volume of the hard disk.
In this material, we will talk about the remaining characteristics of hard drives, which are no less important than the above.
Hard Drive Form Factor
At the moment, two form factors of hard drives are widely used - these are 2.5 and 3.5 inches. The form factor, to a greater extent, determines the dimensions of hard drives. By the way, a 3.5" hard drive can hold up to 5 platters, and a 2.5" hard drive can hold up to 3 platters. But in modern realities, this is not an advantage, since the developers have determined for themselves that it is not advisable to install more than 2 platters in ordinary high-performance hard drives. Although, the 3.5” form factor is not going to give up at all and, in terms of demand, confidently outweighs 2.5” in the desktop segment.
That is, for a desktop system, while it makes sense to purchase only 3.5 ”, since among the advantages of this form factor, one can note a lower cost per gigabyte of space, with a larger volume. This is achieved by a larger platter that, at the same recording density, can hold more data than 2.5”. Traditionally, 2.5" has always been positioned as a laptop form factor, largely due to its size.
There are other form factors as well. For example, many portable devices use 1.8” hard drives, but we will not dwell on them in detail.
Hard drive cache size
Cache memory is a specialized RAM that acts as an intermediate link (buffer) for storing data that has already been read from the hard disk, but has not yet been transferred directly to processing. The very presence of the buffer was caused by a significant difference in speed between the rest of the system components and the hard drive.
As such, a characteristic of HDD cache is volume. At the moment, the most popular hard drives with a buffer of 32 and 64 MB. In fact, buying a hard drive with a large amount of cache memory will not give a twofold increase in performance, as it might seem based on classical arithmetic. Moreover, tests have shown that the advantage of hard drives with 64 MB cache appears quite rarely and only when performing specific tasks. Therefore, if possible, it is worth buying a hard drive with a larger cache, but if this will go to a significant detriment to the price tag, then this is not the parameter that you should focus on in the first place.
Random access time
The hard disk random access time indicator characterizes the time during which the hard drive is guaranteed to carry out a read operation anywhere on the hard disk. That is, for what period of time, the read head will be able to get to the most distant sector of the hard disk. This, to a greater extent, depends on the previously considered characteristic of the speed of rotation of the hard disk spindle. After all, the higher the rotation speed, the faster the head can get to the desired track. In modern hard drives, this figure is from 2 to 16 ms.
Other HDD Specifications
Now briefly and briefly list the remaining characteristics of hard drives:
- Energy consumption - hard drives consume very little. Moreover, the maximum power consumption is often indicated, which takes place only at intermediate stages of operation during peak load. On average, this is 1.5-4.5 W;
- Reliability (MTBF) - the so-called time between failures;
- Data transfer rate - from the outer zone of the disk: from 60 to 114 Mb / s, and from the internal - from 44.2 to 75 Mb / s;
- The number of input / output operations per second (IOPS) - for modern hard drives, this figure is about 50/100 ops / s, with random and sequential access.
So we looked at all the characteristics of hard drives with the help of a small series of articles. Naturally, many parameters intersect and, to some extent, influence each other. But, on the other hand, based on information regarding all these parameters, you can simulate a future device for yourself, and when choosing, clearly understand which of the models should be given priority in your particular case.
But such toys can be obtained from old hard drives, or rather from the components of a hard drive. For example, the wheels are made from a hard drive spindle motor that drives an axle with a read head.
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How to choose a hard drive
The hard disk drive (HDD) is an important element of the system unit. It stores user data and files. To choose the right hard drive, you need to know just a few parameters.
Main characteristics of the hard disk
Hard disk capacity
When choosing a hard drive, the first parameter that you should pay attention to is the volume. Volume - the amount of hard disk space, that is, this parameter displays how much information (movies, documents, folders, etc.) you can write to the hard disk. The volume of modern media is measured in gigabytes or terabytes. The larger the hard drive, the better. It is better to buy a hard drive for one or more terabytes.
Interface
The hard drive is connected to the motherboard via an interface cable. Internal hard drives, connect to a computer via an interface (IDE or SATA). IDE is an outdated interface. Modern hard drives are connected to the computer via the SATA interface. There are several options for the SATA interface: SATA I (up to 1.5 Gb / s), SATA II (up to 3 Gb / s), SATA III (up to 6 Gb / s). The higher the data transfer rate through the interface, the better. The best hard drive interface option is SATA III.
Spindle speed
The speed of data exchange depends on the spindle speed. It is measured in revolutions per minute (RPM). The higher the spindle speed, the better. The best option is 7200 rpm.
Buffer memory (Cache - memory)
Buffer memory is hard disk memory that stores data that has already been read from the hard disk but has not yet been transferred through the interface. The larger the amount of buffer memory, the more likely it is that the necessary data is in it and does not need to be searched on disk. Investigator, increase the speed of the hard drive. At the moment, the maximum amount of memory is 64 MB.
Form Factor
The form factor of a hard drive is its physical dimensions (width, height, thickness). There are two main form factors: 2.5" (2.5") and 3.5" (3.5"). Hard drives with a 2.5” form factor are designed for use in laptops, although they can be inserted into a regular system unit using additional mounts and adapters. Due to the specifics of a laptop, budget 2.5” hard drives in most cases have a spindle speed of 5400 rpm.
3.5” hard drives are designed for installation in a regular system unit. When assembling a home computer, it is better to buy a 3.5” hard drive.
With these tips, you can choose a good hard drive for your computer.
The normal functioning of the operating system and the fast operation of programs on the computer are provided by RAM. Each user knows that the number of tasks that a PC can perform simultaneously depends on its volume. Similar memory, only in smaller volumes, is equipped with some elements of the computer. In this article we will talk about the cache memory of the hard drive.
Cache memory (or buffer memory, buffer) is an area where data is stored that has already been read from the hard drive, but has not yet been transferred for further processing. It stores information that Windows uses most often. The need for this storage arose due to the large difference between the speed of reading data from the drive and the throughput of the system. Other elements of the computer also have a similar buffer: processors, video cards, network cards, etc.
Cache volumes
Of no small importance when choosing an HDD is the amount of buffer memory. Usually these devices are equipped with 8, 16, 32 and 64 MB, but there are buffers for 128 and 256 MB. The cache gets reloaded quite often and needs to be purged, so more is always better in this regard.
Modern HDDs are mainly equipped with 32 and 64 MB cache memory (a smaller amount is already rare). This is usually enough, especially since the system has its own memory, which, coupled with RAM, speeds up the hard drive. True, when choosing a hard drive, not everyone pays attention to a device with the largest buffer size, since the price for such is high, and this parameter is not the only determining one.
The main task of the cache
The cache is used to write and read data, but, as already mentioned, this is not the main factor in the efficient operation of the hard drive. It is also important here how the process of exchanging information with the buffer is organized, as well as how well the technologies that prevent the occurrence of errors work.
Buffer storage contains data that is used most frequently. They are loaded directly from the cache, so performance increases several times. The point is that there is no need for physical reading, which involves direct access to the hard drive and its sectors. This process is too long, as it is calculated in milliseconds, while data is transferred from the buffer many times faster.
Benefits of Cache
The cache is fast processing data, but it has other advantages. Hard drives with large storage can significantly offload the processor, which leads to its minimal use.
Buffer memory is a kind of accelerator that ensures fast and efficient operation of the HDD. It has a positive effect on software startup when it comes to frequent access to the same data, the size of which does not exceed the size of the buffer. For a normal user, 32 and 64 MB are more than enough. Further, this characteristic begins to lose its significance, since when interacting with large files, this difference is insignificant, and who wants to overpay for a larger cache.
Find out the size of the cache
If the size of a hard drive is a value that is easy to find out, then the situation with buffer memory is different. Not every user is interested in this characteristic, but if such a desire arose, it is usually indicated on the packaging with the device. Otherwise, you can find this information on the Internet or use the free HD Tune program.
The utility, designed to work with HDD and SSD, is engaged in reliable data deletion, device status assessment, error scanning, and also provides detailed information about the characteristics of the hard drive.
In this article, we talked about what buffer memory is, what tasks it performs, what its advantages are, and how to find out its volume on a hard drive. We found that it is important, but not the main criterion when choosing a hard drive, and this is a positive thing, given the high cost of devices equipped with a large amount of cache memory.