Cache memory or as it is called hard disk buffer memory. If you do not know what it is, then we will be happy to answer this question and tell you about all the available features. This is a special type of RAM that acts as a buffer for storing previously read but not yet transmitted data for further processing, as well as for storing information that the system accesses most often.
The need for transit storage arose due to the significant difference between the throughput of the PC system and the speed of reading data from the drive. Also, cache memory can be found on other devices, namely in video cards, processors, network cards, and others.
The volume of the buffer deserves special attention. Often, HDDs are equipped with 8, 16, 32 and 64 MB caches. When copying large files between 8 and 16 MB, a significant difference in terms of performance will be noticeable, but between 16 and 32 it is already less noticeable. If you choose between 32 and 64, then there will be almost none at all. It must be understood that the buffer often experiences heavy loads, and in this case, the larger it is, the better.
Modern hard drives use 32 or 64 MB, less today can hardly be found anywhere. For a normal user, both the first and second values will suffice. Moreover, in addition to this, performance is also affected by the size of its own cache built into the system. It is he who increases the performance of the hard drive, especially with a sufficient amount of RAM.
That is, in theory, the larger the volume, the better the performance and the more information can be in the buffer and not load the hard drive, but in practice everything is a little different, and the average user, except in rare cases, will not notice much difference. Of course, it is recommended to choose and buy devices with the largest size, which will greatly improve the performance of the PC. However, this should be done only if financial possibilities allow.
It is designed to read and write data, however, on SCSI drives, permission to write caching is rarely needed, since the default setting is that write caching is disabled. As we have already said, volume is not a decisive factor for improving work efficiency. To increase the performance of the hard drive, it is more important to organize the exchange of information with the buffer. In addition, it is also fully affected by the functioning of the control electronics, prevention of occurrence, and so on.
The most frequently used data is stored in the buffer memory, while the volume determines the capacity of this most stored information. Due to the large size, the performance of the hard drive increases significantly, since the data is loaded directly from the cache and does not require physical reading.
Physical reading - direct system access to the hard disk and its sectors. This process is measured in milliseconds and takes a fairly large amount of time. At the same time, the HDD transmits data more than 100 times faster than when requested by physically accessing the hard drive. That is, it allows the device to work even if the host bus is busy.
Buffer memory has a number of advantages, the main of which is fast data processing, which takes a minimum amount of time, while physical access to the sectors of the drive requires a certain time until the disk head finds the required data section and starts reading them. Moreover, hard drives with the largest storage can significantly offload the computer's processor. Accordingly, the processor is used minimally.
It can also be called a full-fledged accelerator, since the buffering function makes the hard drive much more efficient and faster. But today, with the rapid development of technology, it is losing its former importance. This is due to the fact that most modern models have 32 and 64 MB, which is enough for the normal functioning of the drive. As mentioned above, you can overpay the difference only when the difference in cost corresponds to the difference in efficiency.
In conclusion, I would like to say that buffer memory, whatever it is, improves the performance of a particular program or device only if the same data is repeatedly accessed, the size of which is no larger than the cache size. If your work at the computer involves programs that actively interact with small files, then you need an HDD with the most storage.
All you need is to download and install the free program HDTune. After starting, go to the "Information" section and at the bottom of the window you will see all the necessary parameters.
If you are buying a new device, then all the necessary characteristics can be found on the box or in the attached instructions. Another option is to look online.
There is now a great abundance of hard drives on the shelves of stores, and many pay attention to only one parameter - the volume of the HDD. Volume is far from the only indicator to focus on. In the process of choosing a hard drive, first of all, you need to decide on the goals - why it is bought:
main-system- to install the operating system. The priority of choice should be, first of all, the speed of reading / writing data;
additional-storage- as a volumetric storage of various files: video, photo, music.
We think the HDD device is familiar to everyone, but let's refresh our knowledge a bit: how does the HDD work?
The next step is to determine the amount of hard disk we need. The amount of information that we store on a PC is constantly growing and often the disk is quickly filled with various files (games, photos, videos, etc.). Therefore, if you plan to install only one disk on your home PC, it is better to buy a larger HDD.
Note:
for a home computer, hard drives have a Form factor of 3.5 inches, for laptops there are smaller models - 2.5 inches.
The photo below shows the difference between a 3.5" HDD and a 2.5" HDD.
Attention! We do not recommend:
1. Buy HDD models released recently. Such hard drives, released to the market during the first months, according to statistics, have the largest% of defects. It takes an average of 2-4 months for manufacturers to identify and eliminate errors in hardware and software, then improved models go to retail. Plus, add a few more months of delivery to the CIS market.
2. Top models, with the maximum volume, usually consist of several plates (pancakes), which entails a number of negative points, as we will point out below.
The speed of the hard drive depends on several factors, we will place them in order of priority.
1. The number of hard disk platters.
Modern discs are produced on the 1st, 2nd, 3rd, 4th plates. For example, there is a 1TB HDD that consists of one 1TB platter or with the same HDD volume (1TB) of only two 500 GB platters. Accordingly, we recommend choosing a hard drive on one plate, with the same volume.
Firstly, one plate has more information recording density, and hence the reading speed is greater than from two or more plates. Less time is needed to position the head and read information, and this directly affects the performance of the operating system.
Secondly, for a “one-pancake” disk, less mechanics are required, which means less noise and wear of working elements, and the risk of failure of one or another mechanism is reduced.
Thirdly, less mechanics involved leads to a reduced amount of heat generation. This is also an important aspect. Especially on hot summer days, when the computer's cooling system is not efficient and the air temperature inside the case rises significantly. Overheating of the hard drive leads to a gradual failure of the magnetic surface (deformation), which is fraught with loss of information.
You can find out the number of plates using a Google or Yandex search for a search query: how many plates ST1000DM003
2. Spindle speed.
The spindle speed of standard HDDs is 5400 rpm and 7200 rpm, models with variable rotation speed from 5400 rpm to 7200 rpm are also available. Hard drives with a speed of over 7200 rpm (10000 and 15000) - designed for servers and enthusiasts, as a rule, they are rare in stores, and have a narrow specialization.
The higher the spindle speed, the higher the speed of reading / writing information. But on the other hand, 5400 rpm drives are a little quieter than 7200 rpm.
Drives with a speed of 7200 rpm are worth buying if the HDD will be used as a system one, i.e. the operating system will be installed on it.
And we recommend buying 5400 rpm as an additional one - for storing various information (music, movies, etc.) Read / write speed, in this case, is not so important, and savings in price and noise can be useful.
A compromise solution between speed and noise level are discs with automatic disc speed control. But still, as a system drive, not a very good solution.
3. Buffer (cache) HDD.
The third factor that greatly affects the speed of the hard drive is the buffer size. The larger the buffer size, the higher the speed of data exchange with the HDD. Today it is desirable to purchase hard drives as a system drive with a buffer of at least 64 MB.
And for HDD as a media storage, 32MB is enough.
But if we take into account that the difference in price between a HDD with a 32MB buffer and a 64MB one is sometimes no more than 3-5 USD, then an HDD with a 64MB cache will be the best choice.
4. HDD connection interface.
There are several interfaces for connecting a hard drive, the most common are IDE (PATA) and SATA. But modern HDDs are produced mainly with SATA.
The IDE interface is obsolete and new motherboards do not have such a connector. Therefore, if you are upgrading an old computer and want to keep your old HDD, make sure it has a SATA interface.
SATA interface is divided into three versions:
- SATA I(one) with data rates up to 1.5 Gbps
- SATA II(two) up to 3 Gbps, per mat. boards often has the designation Sata_3Gb
- SATA III(three) up to 6 Gb/s, per mat. boards are often denoted Sata_6Gb
But this is the data transfer rate of the SATA interface itself, i.e. the speed of data exchange between the HDD buffer and the motherboard controller.
The speed of reading / writing from the plates of the HDD itself does not yet exceed 3 Gb / s, i.e. SATA II standard.
SATA I, SATA II and SATA III connectors are externally and structurally the same, and they are backwards compatible with each other, but the data transfer rate is different.
For example, a SATA III HDD is suitable for a motherboard with a SATA I interface, only the bandwidth will drop to the SATA I level (1.5 Gb / s).
Important! Very often they confuse the interface and data transfer rate - SATA 3 (III) and SATA 3 Gb / s are not the same thing!
SATA 3 (III) - this is the SATA III interface with data transfer rates up to 6 Gb / s.
SATA 3 Gb/s is the data transfer rate for the SATA II interface.
Now, knowing the main characteristics of a hard drive, let's try to determine them in practice according to the specifications indicated in the price lists of stores.
Hard drive (drive) 3.5" 1TB Seagate (ST1000DM003) 7200 rpm, 64 MB, SATA III, Barracuda
3,5"
- Form factor, i.e. for desktop PC
1TB- 1 terabyte hard drive
Seagate- manufacturing firm
ST1000DM003– model and manufacturer code
7200 rpm– spindle speed
64MB- buffer size
SATA III– SATA III connection interface
Barracuda– a series of HDDs from one manufacturer
Summary of Hard Drive Selection:
1. Decide on the amount of HDD we need.
2. Choose models made on the 1st plate ("pancake")
3. Weed out models by spindle speed
4. Then choose with the maximum buffer size
5. Checking the connection interface
6. We decide on the HDD manufacturer.
Published by the hard drive.
Also, they did not bypass the HDD interface, where the main features and differences were considered SATA interface and legacy IDE. And of course, they did not forget, perhaps, the most important characteristic - this hard disk capacity.
In this material, we will talk about the remaining characteristics of hard drives, which are no less important than the above.
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 of a drive, 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.
Cache- This 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 memory 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 memory, but if this will significantly damage the price tag, then this is not the parameter that you should focus on in the first place.
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.
Now briefly and briefly list the remaining characteristics of hard drives:
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 basis of 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.
Buffer impact 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 look at the price lists showed that the price difference for disks of the same capacity with different buffer sizes in Moscow now ranges from $3 to $19 and depends on the manufacturer and seller. In this article, we will try to show the impact of the internal buffer size on hard drive performance.
We will compare performance using the HDS722516VLAT20 and HDS722516VLAT80 hard drives from the Deskstar 7K250 family from Hitachi as an example. To be more precise, since last year, Hitachi's new division HGST (Hitachi Global Storage Technologies) has been producing hard drives, formed as a result of combining its own disk production and capacities acquired from IBM. Both disks have a capacity of 160 GB and completely repeat each other in terms of the design of the mechanical part. The tested disks had the same firmware version - V340A60A and differed only in the size of the internal buffer (2 and 8 MB, respectively).
We performed a performance comparison 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 (2S512 MB Kingston PC2700 DDR SDRAM);
Hard drive Hitachi Deskstar IC35L090AVV207-0.
The tested disks were connected in turn as a Secondary Master.
To compare performance, we took tests that simulate the operation of the disk subsystem in real conditions and differ in the way performance is assessed:
Ziff Davis WinBench 99v. 2.0;
Futuremark PCMark2004;
FileCopy Testv. 0.5.3 (developed by F-Center).
In the Ziff Davis WinBench 99 v. 2.0 determines 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 disk access time and a graph of reading speed versus data location on the disk (Fig. 1 and 2).
As expected, the disks have the same access time (Table 1) and the graphs of read speed versus data location on the disk for both disks are the same. In terms of performance in all subtests, the HDS722516VLAT80 is ahead, and we can say that this advantage is completely determined by the work of the buffer. As can be seen from Table. 1, when using the FAT-32 file system, the effect of the buffer is usually more noticeable.
Futuremark's PCMark04 test suite is based on real-world applications and is designed to provide a detailed examination of 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, 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 trace processing speed, measured in megabytes per second. Four traces are used, reproducing the operation of the hard disk when performing 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 experience. 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 copy operations and least of all on operating system loading.
FileCopy Test 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 disk area to another. The results show the operation time and 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 for 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. The table shows that the impact of buffer size on hard disk performance depends on the operation being performed and the average file size being processed. So, when writing and reading large files (ISO pattern) are 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, it can be seen that increasing the buffer size gives a significant performance boost for most operations. Only when writing and reading large files, that is, in a mode where the disk actually works in sequential read / write mode, did the buffer size have no effect on performance.
It is possible that 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 drive with an increased buffer in a computer is more profitable in terms of investment efficiency.
Greetings, dear readers! For normal people, whose consciousness has not yet been clouded by familiarity with computer technology, the first association that arises with the word "winchester" is the famous hunting rifle, extremely popular in the United States. Computer scientists, on the other hand, have completely different associations - this is how most of us call a hard drive.
In today's publication, we will analyze what hard disk buffer memory is, why it is needed and how important this parameter is for performing various tasks.
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 via a network connection, and working documents will be 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 disk. The plate is covered with a layer of ferromagnet (usually chromium dioxide), the clusters of which remember one or zero due to magnetization and demagnetization. There can be several such plates on one axis. For rotation, a small high-speed electric motor is used.
Unlike the gramophone, in which the needle touches the record, the reading heads do not adjoin the disks closely, 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 the 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 creativity of the computer owner), it is recommended to make a backup copy, or rather several at once.
Buffer memory or cache is a special kind of RAM, a kind of “layer” between a magnetic disk and PC components that process data stored on a hard drive. It is intended for smoother reading of information and storage of data that is currently most often accessed by the user or the operating system.
What affects the size of the cache: the more data it can fit, the less often the computer has to access the hard drive. Accordingly, the performance of such a workstation increases (as you already know, in terms of speed, the magnetic disk of the hard drive significantly loses to the RAM chip), as well as indirectly the life of the hard disk.
Indirectly, because different users operate 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.
Guessed why? That's right, because of the limited number of cycles of rewriting information on the HDD. 
Before you can see the amount of 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.
A logical question arises: what is the best buffer memory for a home computer and what does it give in practical terms? Naturally, more is desirable. However, the hard drive manufacturers themselves impose restrictions on the user: for example, a hard drive with 128 MB of buffer memory will cost significantly higher than the average.
It is 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 get by 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 buffer memory is enough.
As a "golden mean" I can recommend the Toshiba P300 1TB 7200rpm 64MB HDWD110UZSVA 3.5 SATA III hard drive - here the average cache size, but the capacity of the hard drive itself is quite enough for a home PC. Also, for the sake of completeness, I recommend that you familiarize yourself with the publications of the disks and, as well as which ones are on hard disks.
