How to choose a hard drive so that it works well and for a long time. What is hard disk cache Buffer size of hard disk

Greetings, dear readers! For normal people, whose consciousness has not yet been clouded by familiarity with computer technology, the first association with the word "Winchester" arises - the famous hunting rifle, which is extremely popular in the United States. Computer scientists have completely different associations - that's what most of us call a hard drive.

In today's publication, we will analyze what the hard disk buffer memory is, what it is for and how important this parameter is for performing various tasks.

How a hard drive works

The HDD is essentially a drive that stores all user files, as well as the operating system itself. Theoretically, this detail can be dispensed with, but then the OS will have to be loaded from removable media or over a network connection, and working documents stored on a remote server.

The base of the hard drive is a round aluminum or glass plate. It has a sufficient degree of rigidity, which is why the part is called a hard drive. The plate is covered with a layer of ferromagnet (usually chromium dioxide), the clusters of which memorize one or zero due to magnetization and demagnetization. There can be several such plates on one axis. A small high-speed electric motor is used for rotation.

Unlike a gramophone, in which the needle touches the plate, the read heads do not adjoin the disks close to them, leaving a distance of several nanometers. Due to the absence of mechanical contact, the service life of such a device is increased.

However, no part lasts forever: over time, the ferromagnet loses its properties, which means it leads to a loss of hard disk space, usually along with user files.

That is why, for important or dear to the heart data (for example, a family photo archive or the fruits of the computer owner's creativity) it is recommended to make a backup copy, and preferably several at once.

What is cache

Buffer memory or cache is a special type of random access memory, a kind of "layer" between the magnetic disk and the PC components that process the data stored on the hard drive. It is intended for smoother reading of information and storage of data, which at the moment is most often accessed by the user or the operating system.

What affects the size of the cache: the larger the amount of data in it, the less often the computer has to access the hard disk. Accordingly, the performance of such a workstation increases (as you already know, in terms of performance, the magnetic disk of the hard drive is significantly inferior to the RAM chip), as well as, indirectly, the life of the hard disk.

Indirectly, because different users use the hard drive in different ways: for example, a movie lover who watches them in an online cinema through a browser will theoretically have a hard drive longer than a movie fan who downloads movies with a torrent and watches them using a video player.

Guess why? That's right, because of the limited number of data rewriting cycles on the HDD.

How to see the buffer size

Before you can see the size of the cache, you will have to download and install the HD Tune utility. After starting the program, the parameter of interest can be found in the "Information" tab at the bottom of the page.

Optimal sizes for different tasks

A natural question arises: which buffer memory is better for a home computer and what gives it in practical terms? Naturally, more is desirable. However, the hard drive manufacturers themselves impose a restriction on the user: for example, a hard drive with 128 MB of buffer memory will cost significantly higher than average.

It is on this amount of cache that I recommend focusing on if you want to build a gaming computer that will not become obsolete in a couple of years. For simpler tasks, you can do with simpler characteristics: 64 MB is enough for a home media center. And for a computer that is used purely for surfing the Internet and running office applications and simple flash games, 32 MB of buffer memory is quite enough.

As a "golden mean" I can recommend the Toshiba P300 1TB 7200rpm 64MB HDWD110UZSVA 3.5 SATA III hard drive - here the cache size is average, but the capacity of the hard disk itself is quite enough for a home PC. Also, for the sake of completeness, I recommend that you familiarize yourself with the publications of disks and, as well as which ones on hard disks.

Impact of buffer on hard drive performance

Vladimir Leonov

Modern series of hard drives from all manufacturers can be divided into two categories, differing in the size of the internal buffer (2 or 8 MB). A review of the price lists showed that the difference in the price of disks of the same size with different buffer sizes in Moscow now ranges from $ 3 to $ 19 and depends on the manufacturer and the seller. In this article, we will try to show the effect of internal buffer size on hard drive performance.

We will compare the performance using the example of HDS722516VLAT20 and HDS722516VLAT80 hard drives from the Deskstar 7K250 family from Hitachi. To be more precise, since last year, Hitachi has been manufacturing hard drives in a new division, HGST (Hitachi Global Storage Technologies), formed as a result of the merger of its own disk production and capacities acquired from IBM. Both disks have a volume of 160 GB and completely repeat each other in mechanical design. The tested drives had the same firmware version - V340A60A and differed only in the size of the internal buffer (2 and 8 MB, respectively).

We compared performance under the Windows XP Professional.SP1 operating system on a computer with the following configuration:

Motherboard - MSI 875P Neo (MS-6758);

Processor - Intel Pentium 4 3.06 GHz (533 FSB);

Memory - 1 GB (2Ѕ512 MB Kingston PC2700 DDR SDRAM);

Hard drive - Hitachi Deskstar IC35L090AVV207-0.

The tested disks were connected in turn as Secondary Master.

To compare performance, we took tests that simulate the operation of the disk subsystem in real conditions and differ in the way of assessing performance:

Ziff Davis WinBench 99 v. 2.0;

Futuremark PCMark2004;

FileCopy Test v. 0.5.3 (developed by F-Center).

In the Ziff Davis WinBench 99 v. 2.0 measures the performance of the disk subsystem when running real applications. This is a good test, but, unfortunately, it is no longer supported by the developer and the versions of the applications used in the test are very outdated. In addition to performance, the test determines the average access time to the disk and a graph of the dependence of the read speed on the location of the data on the disk (Fig. 1 and 2).

As expected, the disks have the same access time (Table 1) and the graphs of the read speed versus the data location on the disk for both disks are the same. The HDS722516VLAT80 hard drive is ahead in performance in all subtests, and we can say that this advantage is completely determined by the buffer operation. As you can see from the table. 1, when using the FAT-32 file system, the effect of the buffer is usually more noticeable.

Futuremark's PCMark04 benchmark suite is based on real-world applications and is designed to provide detailed insights into computer performance. The package consists of several sections, one of which is designed to determine the performance of the disk subsystem. To test the disk subsystem, the so-called traces are used - sequences of disk activity recorded in advance on a certain reference computer when performing various tasks. The performance indicator is the processing speed of the trace, measured in megabytes per second. Four traces are used to reproduce the performance of the hard drive in various tasks. The purpose of the tracks is clear from their name. These are loading the operating system, opening and closing several popular applications, copying files and simulating user work. The results are shown in table. 2. As in the previous test, the HDS722516VLAT80 hard drive is ahead. The effect of the increased buffer is most pronounced on the copy operations and least of all on the load of the operating system.

FileCopy Test utility v. 0.5.3 was developed by F-Center specialists and is designed to determine the performance of a hard disk when creating (writing) files on a disk, reading files from a disk and copying files from one part of a disk to another. The results shown are the time to complete the operation and the speed, measured in megabytes per second (MB / s). When creating files, pre-prepared patterns are used - lists containing information about the length and number of files that need to be created. The pattern can be created either manually or automatically from any folder using the Scan option, which makes it easy to create a pattern with a real distribution of files by size. We used the patterns included in the distribution kit of the program. By the name of the patterns, it is easy to guess about their content. The test results are shown in table. 3. It can be seen from the table that the degree of influence of the buffer size on the hard disk performance depends on the operation being performed and the average size of the file being processed. For example, when writing and reading large files (ISO pattern) is performed separately, the buffer size has almost no effect on performance, and when copying such files, the effect of the buffer size is most pronounced.

From the above results, you can see that increasing the buffer size gives a significant performance gain for most operations. Only when writing and reading large files, that is, in a mode when the disk actually operates in sequential read / write mode, the buffer size did not affect performance.

Perhaps, on hard drives from other manufacturers and even on tested hard drives with a different firmware version, the effect of the buffer size will be slightly different, but the difference is unlikely to be significant. In our opinion, installing a hard disk with an increased buffer in a computer is more profitable in terms of investment efficiency.

Which hard drive to choose. Choose the right hard drive to keep it fast, quiet and reliable. Unfortunately, before you have time to look back, the disk is already filled to capacity. There are users who, even after several years, have enough disk space to work for another 10 years.

But this, as a rule, is rather an exception. Many people have a sorely lack of hard disk space, and sometimes just somewhere. Now the computer is not just a typewriter. Many users are engaged in serious projects on it and earn good money on it. And a hard drive, as you know, stores a lot of useful information, so you don't have to buy it anyhow.

Which hard drive to choose

It all depends on what you will be doing on your computer. It is best if your computer has not one hard drive, but two or even three. Read how to install such a disk. On the main disk, you will have an operating system, and on the rest it is better to store your data.

Usually hard disk space is sorely lacking. Do not think that you are the only one. Now I even wonder how 10 GB was enough for me. The most annoying thing is that all the files are needed and expensive, and you don't want to delete anything at all.

Any device has its own parameters and resources, and the computer hard drive is no exception. If you just come to the store and ask for a disc, then you may not be advised what is necessary, but most likely what is more expensive. Why overpay if you can take the same or with the remaining money.

WHERE YOU CAN STORE YOUR DATA EXCEPT HARD DISK

Previously, you could burn your data to a "blank" (CD or DVD) and sleep peacefully. Now everyone has so much information on their computers that it is no longer possible to rewrite everything on a CD. At best, you can rewrite something that is most important.

Still, it's not very convenient. You will not carry with you a whole briefcase of CDs or DVDs and insert one by one into the drive to find the information you need.

You can buy a small but large external drive and carry it with you. But, again, there is no guarantee that it will never "glitch". And then "goodbye" valuable information. I recently did it. But, now is not about that.

External hard drive 2.5 '

Capacity (volume) of the hard drive

An operating system does not need a large disk space. Since the minimum disk size is now on sale is 500 GB, then this is enough for your eyes. But another disc, if you constantly download something from the Internet, you need to take as much volume as possible.

Spindle speed

The operating system needs a disk with a good spindle speed. At low speeds, your operating system will slow down, no matter what memory is, and no matter how smart the microprocessor is.

Everything should be integrated. Otherwise, you will throw money down the drain. You cannot save on hard disk space!

Modern hard disk drives (HDD) 2.5 and 3.5 ”have a spindle rotation speed of 5400 or 7200 rpm. The higher the spindle speed, the higher the speed of the disk.

For a home computer, the speed of the hard disk on which the operating system, graphics programs and your games will be installed must be at least 7200 rpm.

If you buy a disk for an office, then 5400 rpm will be enough. The same speed is also suitable for data storage, i.e. second hard drive, especially since it's cheaper.

There are SAS or SCSI drives, with speeds of 10,000 and 15,000 rpm, but they are used for servers and are not cheap.

SCSI hard drive

But if you have an old computer and an IDE hard drive, then the choice is not large, and you can forget about the good spindle speed of the drive. And finding such a disk is already problematic.

How to identify an old hard drive or not

If your disk has a wide ribbon cable, then this is the IDE interface. They are no longer used in new computers, and the speed of these drives is low.

Cable for connecting an IDE disk

New computers use SATA, SATA 2 and SATA 3 hard drives.

SATA drive cable

The transfer rate of SATA drive is 50% faster than IDE drive.

SATA, SATA 2 and SATA 3 drives are interchangeable. But the data transfer rate of SATA 3 is much better than that of SATA.

Please note that SATA and SATA2 drive cables do not fit SATA3 drive. Their frequency characteristics are different, although the connectors are the same and they will still work. The ribbon cable (cable) for SATA3 is thicker and usually black.

It is also important to know what type of SATA hard drive your motherboard supports, otherwise the drive will not work at full capacity. But this is not critical. But if the motherboard is very old, then it may not support a SATA drive at all, i.e. it will not have a connector for it.

Buffer size or cache size

The next item to select a disk is cache size(buffer memory). There are 8, 16, 32, 64 and 128 MB cache sizes. The higher the number, the better the processing speed.

For data storage, 16 MB is suitable, and for the system it is better to buy from 32 MB. If you are engaged in graphics, then for programs such as photoshop and autocad it is better to take a hard drive with a cache memory - 64 or 128 MB, especially since the difference in price between them is not significant.

Average linear read speed

Linear read speed means the speed of continuous reading of data from the surface of the platter (HDD) and is the main characteristic that reflects the real speed of the disk. It is measured in megabytes per second (Mbps).

Modern HDDs with SATA interface have an average linear read speed from 100 to 140 Mb / s.

The linear read speed of HDD disks depends on the density of data recording on the magnetic surface of the platters and the quality of the disk mechanics.

Access time

This is the speed at which the disk finds the required file after being accessed by the operating system or some program. Measured in milliseconds (ms). This parameter has a big impact on disk performance when working with small files and not a big one when working with large files.

Hard drives have access times from 12 to 18 ms. A good indicator is access time of 13-14 ms (depending on the quality (accuracy) of the disc mechanics).

Now there are new hard drives on the market - SSDs, consisting of only microchips, but they are very expensive and therefore not intended for data storage. They are only good for running programs. SSD drives do not have a spindle, so they are completely silent, do not heat up, and are very fast.

And the most important! Avoid placing hard drives side by side. It is better if there is more space around them, because during operation, they get very hot and can fail from overheating.

Better yet, especially in summer, cool them by opening the computer lid and aiming the fan at them. Overheating for a hard drive is just as destructive as for a video card and microprocessor.

Any disc manufacturer company has discs that are more expensive and cheaper. But this does not mean that firms are hackneyed. Just one product for state employees, and the other for the wealthier. Both those and other discs are made conscientiously, but the parts are made of different materials, which have different wear periods.

Hard drive manufacturers

The main manufacturers of hard disk drives (HDD) are:

Fujitsu- a Japanese company, previously famous for the high quality of its products, is currently represented by a small number of models and is not very popular.

Hitachi- the Japanese company, both earlier and now, is distinguished by stable quality of hard drives. Buying a Hitachi hard drive you will not go wrong, having received good quality for an affordable price.

Samsung- this Korean company. Today Samsung produces the fastest and highest quality HDD disks. They may be priced slightly higher than the competition, but worth it.

Seagate Is an American technology pioneer company. Unfortunately, the quality of hard drives from this company leaves much to be desired.

Toshiba Is a Japanese company. Now it is represented by a small number of models on our market. In this regard, there may be problems in the service of such manufacturers.

Western Digital (WD) Is an American company specializing in the production of hard drives. Lately, the disks of this company do not stand out with outstanding performance, and are very noisy.

It is better to choose between Samsung or Hitachi, as the highest quality, fastest and most stable.

So, the main characteristics of hard drives:

Spindle speed
HDD capacity
Cache size
Average linear read speed
Noise level
Manufacturer

Now you know which hard drive to choose. Unfortunately, shops don't always have a choice, so I prefer to order online. In big cities, there is more choice. Therefore, do not be lazy and study their main characteristics.

Hard disk (hard drive, HDD)- rewritable read only memory (ROM) - the main storage medium in a computer. It stores data: both the operating system and the user's files (programs, games, movies, music, images ...). The memory of the hard disk is not volatile, which explains the possibility of storing data without supplying electricity to the device.

Winchester is a set of one or more sealed disc-shaped plates covered with a layer of ferromagnetic material and readheads in one housing. The plates are driven by a spindle (rotating shaft). The solenoid actuator positions the head for read / write data operations.

The read heads do not touch the disk surface both during reading / writing data (due to an interlayer of the incoming air flow of 5-10 nm, which is formed during very fast rotation), and during disk idle time (the heads are retracted to the spindle or outside the plates ). Due to the lack of contact, the hard drive can be rewritten on average 100 thousand times. Also, the operating time of the disk is influenced by the hermetically sealed case (hermetic zone), due to which a space is created inside the HDD case free of dust and moisture.

The main characteristics of the hard drive: interface, capacity, buffer size, physical size (form factor), random access time, data transfer rate, I / O operations per second, spindle speed, noise level.

The first thing to look for when choosing a hard drive is 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 - its faster counterpart (12 Gbps), backward 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) is the most common hard disk interface. It is on him that you should be guided when choosing a hard drive. There are several variations at the moment. SATA... From a physical point of view, they do not differ (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 here. The larger it is, the better, since more information can be recorded. This characteristic does not affect the performance of the hard drive in any way. User-defined based on the need for storage space. The table below shows the average sizes of the main file types that you should pay attention to when choosing HDD.

Buffer (cache) size... A buffer (cache) is a volatile memory (like RAM) built into the hard disk, designed to smooth out differences in read / write speed, as well as store data that are most often accessed. The larger the 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 "and 2.5". The former is mainly used in desktop computers, the latter 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 to an arbitrary area of the magnetic disk. The parameter ranges from 2.5 to 16 milliseconds. Naturally, the lower the value, the better.

Data 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 order, 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 I / O operations per second> data transfer rate.

Spindle speed- the number of spindle revolutions per minute. Access time and average data transfer rate largely depend on this parameter. The most common rotational speeds are: 5400, 5900, 7200, 10000 and 15000 rpm. The optimal speed for a PC is 7200 rpm.

Noise level hard disk drive is composed of spindle rotation noise and positioning noise. Measured in decibels. This characteristic should be noted from comfort beliefs.

RAID... If you have funds to buy 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 (like multichannel mode for RAM), on the other hand, to protect yourself from the loss of important data.

Bottom line. First of all, you should think about the purpose of the disk, based on this, it will be determined with 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 it will be determined with the spindle rotation speed. The parameters of the data transfer rate, the number of input-output operations per second, and the random access time are selected according to the situation, depending on the need. Pay attention to the noise level if you need comfort.

Today, a common storage device is a magnetic hard disk. It has a certain amount of memory dedicated to storing basic data. It also has a buffer memory, the purpose of which is to store intermediate data. Professionals call the hard disk buffer the term "cache memory" or simply "cache". Let's figure out why the HDD buffer is needed, what it affects and how big it is.

The hard disk buffer helps the operating system temporarily store data that was read from the main memory of the hard drive, but was not transferred for processing. The need for a transit storage is due to the fact that the speed of reading information from the HDD drive and the throughput of the OS differ significantly. Therefore, the computer needs to temporarily store data in the "cache", and only then use them for their intended purpose.

The hard disk buffer itself is not a separate sector, as incompetent computer users believe. It is a special memory chip located on the internal HDD board. Such microcircuits are able to work much faster than the drive itself. As a result, they cause an increase (by several percent) in computer performance that is observed during operation.

It should be noted that the size of the "cache memory" depends on the specific disk model. Previously, it was about 8 megabytes, and this figure was considered satisfactory. However, with the advancement of technology, manufacturers have been able to produce chips with more memory capacity. Therefore, most modern hard drives have a buffer, the size of which varies from 32 to 128 megabytes. Of course, the largest "cache" is installed in expensive models.

How hard disk buffer affects performance

Now we will tell you why the size of the hard drive buffer affects the performance of the computer. Theoretically, the more information will be in the "cache memory", the less often the operating system will access the hard drive. This is especially true for a work scenario when a potential user is processing a large number of small files. They simply move to the hard disk buffer and wait for their turn there.

However, if a PC is used to process large files, then the "cache" loses its relevance. After all, information cannot fit on microcircuits, the volume of which is small. As a result, the user will not notice an increase in computer performance, since the buffer will hardly be used. This happens in cases when programs for editing video files, etc. will be launched in the operating system.

Thus, when purchasing a new hard drive, it is recommended to pay attention to the size of the "cache" only if you plan to constantly deal with the processing of small files. Then you can really notice an increase in the performance of your personal computer. And if the PC will be used for ordinary daily tasks or processing large files, then you can not attach any importance to the clipboard.