Buffer memory MB. Buffer memory: Main characteristics. How to find out the scope of buffer memory on the hard disk

Special attention deserves the volume of buffer. Often, HDD is equipped with cache 8, 16, 32 and 64 MB. When copying large-sized files between 8 and 16 MB, a significant difference in terms of speed will be noticeable, but it is less unnoticed between 16 and 32. If you choose between 32 and 64, it will almost never be it. It is necessary to understand that the buffer often experiences heavy loads, and in this case, than it is more, the better.

In modern hard disks Used 32 or 64 MB, less today can hardly be found somewhere. For a regular user will be enough and the first and second value. Moreover, in addition to this, the performance also affects the size of its own embedded cache system. It is he who increases the performance of a hard disk, especially with a sufficient amount of RAM.

That is, in theory, the larger, the better the performance and the more information may be in the buffer and do not load the hard drive, but in practice everything is a little different, and the usual user except for rare cases will not notice a special difference. Of course, it is recommended to choose and buy devices with the greatest size, which will significantly improve the work of the PC. However, this should be followed only if financial capabilities allow.

Purpose

It is designed to read and write data, however SCSI disks In rare cases, it is necessary to permission to caching the recording, since the default is that the recording caching is prohibited. As we have already spoken, the volume is not a decisive factor to improve the efficiency of work. To increase the performance of the hard drive, more important is the organization of information exchange with buffer. In addition, it is also fully affected by the functioning of control electronics, preventing errors and so on.

In buffer memory, the most frequently used data is stored, while the volume determines the capacity of this most stored information. Due to big size The performance of the winechester increases at times, since the data is loaded directly from the cache and do not require physical reading.

Physical reading is a direct circulation of the system to a hard disk and its sectors. This process is measured in milliseconds and occupies a sufficiently large amount of time. At the same time, the HDD transmits data more than 100 times faster than when requesting by physical access to the Winchester. That is, it allows the device to work even if the host bus is busy.

Main advantages

Buffer memory has a number of advantages, the main of which is the fast data processing, which occupies the minimum amount of time, while the physical access to the drive sectors requires a certain time while the disc head detects the required data plot and start reading them. Moreover, the Winchesters with the highest storage, allow you to significantly unload the computer processor. Accordingly, the processor is activated as minimal.

It can also be called a full-fledged accelerator, since the buffering function makes the hard drive work much more efficiently and faster. But today, in the conditions of the rapid development of technology, it loses its former value. 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, it is possible to overpay the difference only when the difference in cost corresponds to the difference in efficiency.

Finally, I would like to say that buffer memory, whatever it is, improves the work of a program or device only if there is a multiple appeal to the same data, the size of which is not more than the size of the cache. If your computer work is connected with programs that are actively interacting with small files, then you need HDD with the highest storage.

Register memory

Do not confuse with ECC memory, although the register modules always use ECC.

Register Memory (Eng. Registered Memory, RDIMM, Sometimes Buffered Memory) - Computer View random access memoryThe modules of which contain the register between memory chips and the memory controller. The presence of registers reduces the electrical load on the controller and allows you to set more memory modules in one channel. Register memory is more expensive due to the smaller production and availability of additional microcircuits. Usually used in systems requiring scalability and fault tolerance to the detriment of cheapness (for example - in servers). Although most of the memory modules for servers are register and uses ECC, there are modules with ECC but without registers (UDIMM ECC), they are also operational and in desktop systems. Register modules without ECC does not exist.

Due to the use of registers, an additional delay occurs when working with memory. Each reading and record is buffered in the register for one clock, before you fall from the memory bus to the DRAM chip, so register memory is considered one clock slower than the non-regular (UDIMM, unregistered DRAM). For SDRAM memory, this delay is essential only for the first cycle in the query series (BURST).

Only control signals and address settings are subjected to buffer memory.

Buffered Memory (Buffered Memory) is analogous term to designate register memory.

Some new systems use fully buffered FB-DIMM memory, in which not only control lines are buffering, but also data lines using a special AMB controller located on each memory module.

Register memory technique can be applied to various generations of memory, for example: DDR DIMM, DDR2 DIMM, DDR3 DIMM, DDR4 DIMM

The principle of hard disk operation

HDD is essentially a drive on which all user files are stored, as well as the operating system itself. Theoretically, without this part, you can do without it, but then the OS will have to load from removable media or by network connection, and stored working documents on a remote server.

Winchester base - round aluminum or glass plate. It has a sufficient degree of rigidity, therefore the item is called a hard disk. The plate is covered with a layer of ferromagnetic (usually chromium dioxide), the clusters of which are remembered or zero due to magnetization and demagnetization. On one axis there may be several such plates. For rotation, a small high-risk electric motor is used.

Unlike a gramophone, in which the needle concerns the plate, the reading heads are not adjacent to the disks, leaving the distance to several nanometers. Due to the lack of mechanical contact, the service life of such a device increases.

However, no detail serves forever: over time, the ferromagnet loses properties, which means, leads to loss of hard disk, usually along with user files.

That is why, for important or expensive heart of data (for example, family photo archives or fruits of creativity of the computer owner), it is recommended to do backup, and better several at once.

What is cache

Buffer memory or cache is a special type of RAM, a peculiar "layer" between the magnetic disk and components of the PC, which processed the data stored on the hard drive. It is intended for more smooth reading of information and storing the data to which the user or operating system is most often referred to.

What is affected by the cache size: the larger amount of data in it fit, 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 speed, the magnetic drive of the hard drive significantly loses the RAM microcircuit), as well as indirectly the life of the hard disk.

Indirectly because different users exploit the hard drive in different ways: for example, a fan of films that looks at them in the online cinema through the browser, theoretically hard will last longer than that of a movie woman swinging the movies torrent and brings them through the video player.

Guessed why? That's right, due to the limited number of cycles of rewriting information on HDD.

Optimal dimensions for various tasks

There is a lawsager question: what buffer memory is better for a home computer and what does it give in a practical plan? Naturally, preferably more. However, the manufacturers of Winches themselves themselves are imposed on the user: for example, HARD with 128 MB of buffer memory will cost significantly higher than the average.

It is on such a volume of cache that I recommend to navigate if you want to assemble a gaming computer that does not endure after a couple of years. For problems, it is easier for tasks and easier: a home media center with a head is enough and 64 MB. And for a computer that is used purely for surfing on the Internet and launch office applications And simple flash games, quite enough and buffer memory with a volume of 32 MB.

As the "Golden Mid" I can recommend the Winchester Toshiba P300 1TB 7200RPM 64MB HDWD110UZSVA 3.5 SATA III - here the average cache size, but the tank of the hard disk is quite enough for the home PC. Also, for completeness, I recommend to familiarize yourself with the publications about the best hard drive manufacturers and HDD rating, as well as which connectors are on hard drives.

What makes cache in your hard drive?

Now take a look at the principle of operation of the HDD hard disk, which is alleged in compact devices with solid-state drives, but perhaps will still remain a major storage tool.

So, there are several rotating magnetic plates inside it. The reading heads move to the desired sector and record or read information. (Visually, all this reminds Vinyl player).

As you can see, the mechanisms in this device Absolutely, and despite the ultra-high speed of their movement, the appeal to the HDD for the next portion of the data occupies a lot (by the performance of the capituization of the CPU) time. It aggravates the fact that the information is recorded on the surface of the disks by fragments that can be located in different places and on separate plates.

So so that the system does not engage in the draft work of folding together individual blocks of information, this work It was decided to get the most hard disk, which will bind them together in their own cache. Conditionally, it is possible to describe such an analogy of this process: the boss took all information on the transaction and subordinate, in order not to carry into the office on a separate document, pre-collects and grows them in the department.

Immediately add that in SSD the problem of inertness of reading information is not so critical. Here, the speed of this process is several orders of magnitude higher. But in connection with the fragmentation of the record of large amounts of data, the optimization of work with them is also necessary. Therefore, in some solid-state drives Cache is also present.

Cache memory is one of the HDD parameters

Go directly to the gland to find out what the hard disk cache is.

In HDD, in addition to mechanical parts there is a control board with connectors. It contains a special microcircuit, which is high-speed access memory. This is cache. Its volume is relatively not large and in conventional hard drives there can be 32 and 64 megabytes (in some old models there are still values \u200b\u200bof 8 or 16 MB). This is enough to make the work of the personal computer system smooth and fast.

How much better you ask? It seems to me that the answer is obvious, but some bloggers note that a significant difference between 32 and 64 MB in the process of using HDD is almost impossible to catch. I believe that with the increase in the complexity of the software tasks, it will still be noticeable.

And if you expect to squeeze out of your PC maximum, then it costs to install the best of what you can afford. In favor of such a position, it is also the fact that the server hard disks are already used by the cache of 128 and even 256 MB. I think this fact will help you answer the question: what does the volume of buffer affect?

It turns out that the w drive cache matters, and this parameter must be taken into account when choosing and buying HDD. How to find out this figure for new and already acquired devices? Easier and more reliable to clarify the model marking and on the manufacturer's website official information. Also, the volume of the buffer of the winchester can suggest a program of type AIDA64.

Algorithm of the Hard Disk Cache

Let's figure out how the buffer memory of the Winchester works. The main consumer located on it is the processor. The following scheme works further:

• the CPU receives a request to the controller, which by certain labels identifies the data and immediately checks their presence in the hard disk cache. If any, the appeal to the HDD is not produced;
  in case of absence necessary information It is performed to read from the hard drive, and the nearby data are additionally captured, which, with a high probability, can also be needed in subsequent requests;
• under this information block in the cache, the corresponding place of a certain size is released. Such a procedure is a difficult task, since the computer must sacrifice any data from the buffer. The choice is carried out with the help of several algorithms that determine the degree of "unobability". To do this, an assessment is made to the limit of the latest use of information, by frequency of appeal to it.
• actual data is loaded to free space. Then the process of interaction of the processor and hard disk continues again on this algorithm.

And one more point: Cache Winchester is an energy-dependent memory. Therefore, before turning off the PC, the system copies the cache information directly to the HDD itself, and after turning on it back. When an emergency de-energization of the computer does not happen.

Here we smoothly approached the frequently asked question: Is it necessary to clean the cache memory of the hard disk? If you are about those 64 megabytes that are stored on the chip, then my answer: no, it is meaningless. If you want so much, just cut down the computer from the outlet and turn on again. Was it easier for you? Another thing - cache files that leave on HDD different programs. Now they have an impressive volume over time and it is possible to simply use the CCleaner type app.

Data caching with a hard disk chip is intended to provide a system with solid data blocks, which significantly increases its speed. But in addition to a separate board, the buffering information can also be carried out by other ways well known to us.

• RAM is essentially the cache in relation to HDD. She is several orders of magnitude, but her speed of her work still loses its own module of Winchester.
• The hard disk highlights the sector for temporary files that will be recorded without fragmentation. This is called the paging file (virtual memory) and its dimensions can exceed the RAM volume.

But it is already completely different devices that require a separate article. And about the most cache of the hard disk, I have nothing to add and I will say goodbye to you.

Send me your questions, prompt interesting topics, and I will try to please you again on the pages of my blog.

See you soon!

Today, the common information drive is magnetic hDD. It has a certain amount of memory intended for storing basic data. It also has buffer memory, the purpose of which is to keep intermediate data. Professionals call the hard disk buffer with the term "Cache Memory" or simply "cache." Let's deal with why the HDD buffer is needed on what affects and what is the size.

The hard disk buffer helps the operating system to temporarily store the data that was read from the main memory of the hard drive, but were not transferred to the processing. The need for transit storage is due to the fact that the speed of reading information from the HDD of the drive and the OS bandwidth differs significantly. Therefore, the computer is required to temporarily save the data in the "cache", and only then use them to be destined.

Directly the hard disk buffer itself is not separate sectors, as the incompetent believes computer Users. It is special memory chips located on the HDD internal board. Such microcircuits are able to work much faster than the drive itself. As a result, the increase (a few percent) of the computer performance observed during operation is determined.

It is worth noting that the size of "Cache Memory" depends on specific model disk. Previously, it was about 8 megabytes, and such an indicator was considered satisfactory. However, with the development of technologies, manufacturers were able to produce chips with larger memory. Therefore, most modern hard drives possess a buffer, the size of which varies from 32 to 128 megabytes. Of course, the greatest "cache" is installed in expensive models.

What effect is the hard disk buffer for performance

Now let's tell why the size of the hard drive buffer affects the performance of the computer. Theoretically, the more information will be in "Cache Memory", the less the operating system will turn to the Winchester. This is especially true for the work script when the potential user is engaged in processing a large number of small files. They simply move to the hard disk buffer and there are waiting for their turn.

However, if the PC is used to handle large files, then the "cache" loses its relevance. After all, the information will not be able to fit on chips, the volume is small. As a result, the user will not notice an increase in computer performance, since the buffer will not be used. This happens in cases where programs will be launched in the operating system to edit video files, etc.

Thus, when purchasing a new hard drive, it is recommended to pay attention to the size of the "cache" only in cases if you plan to constantly process small files. Then it will really notice to increase the productivity of your personal computer. And if the PC will be used for ordinary everyday tasks or processing large files, then you can not give the exchange buffer any value.

Selecting a hard disk for PC is a very responsible task. After all, it is the main storage facility and your personal information. In this material we will talk about the key characteristics of the HDD, which you should pay attention to when buying a magnetic drive.

Introduction

Buying a computer, many users often focus their attention on the characteristics of such components such as a monitor, processor, video card. And such an integral component of any PC, like a hard disk (in computer slang - Winchester), buyers are often acquired, guided by only its volume, practically neglecting other important parameters. Nevertheless, it should be remembered that the competent approach to the choice of a hard disk is one of the safeguards of comfort with further work at the computer, as well as saving funds in which we are so often crammed.

Hard disk or hard disk drive (HDD) is a major data storage in most modern computers on which not only the information required by the user, including films, games, photos, music, but also the operating system, and all software installed. Therefore, in fact, to choose a hard disk for a computer should be treated with due attention. Remember that when the failure of any PC element can be replaced. The only negative moment in this situation is additional financial costs for repairing or buying a new part. But the breakdown of the hard disk, in addition to unforeseen costs, can lead to the loss of all your information, as well as the need to re-install operating system and all the required programs. The main purpose of this article is to assist novice PC users in choosing a hard disk model that would best comply with the requirements for specific "users" to the computer.

First of all, you should clearly decide on which computer device will be installed Winchester and to implement what purpose it is planned to use this device. Based on the most common tasks, we can conditionally divide them into several groups:

• Mobile computer for shared tasks (work with documents, surfing across the unburses of worldwide web, data processing and working with programs).
• Productive mobile computer for games and resource-intensive tasks.
• Desktop computer for office tasks;
• Productive desktop computer (work with multimedia, games, audio, video and image processing);
• Multimedia player and data warehouse.
• To assemble an external (portable) drive.

In accordance with one of the listed options for operating a computer, you can start selecting suitable model Hard disk.

Form factor

Form factor is the physical size of the hard disk. To date, most of the storage devices for home computers have a width of 2.5 or 3.5 inches. The first, which are smaller, are intended for installation in laptops, the second - in stationary system blocks. Of course, if you wish, a 2.5-inch disc can be installed in a desktop PC.

There are also smaller magnetic storage devices with dimensions 1.8 ", 1" and even 0.85 ". But the data of the hard drives are distributed much less 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 speak about them in this material.

The smaller the size of the disk, the more easier and the less power is required for its operation. Therefore, the hard drives of the form factor 2.5 "almost completely replaced with 3.5-inch models in external drives. After all, for the work of large external disks, additional power is required from the electrical outlet, while the youngest fellow is content only by 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 size for these purposes. It will be a lighter and compact solution, and the power supply does not have to carry with me.

As for the installation of 2.5-inch disks in the stationary system unitThis solution looks ambiguous. Why? Read on.

Capacity

One of the main characteristics of any drive (in this regard, the hard drive is no exception) is its capacity (or volume), which today has four terabytes (in one Terabive 1024 GB). Some more than 5 years ago, a similar volume could seem fantastic, however, the current assemblies of the OS, modern software, high-resolution videos and photos, as well as three-dimensional computer video games, having a rather solid "weight" need a large capacity of the hard drive. So, some modern games for normal functioning require 12 and even more gigabytes of free space on the hard disk, and a semi-third-hour HD-quality film may require for storage and over 20 GB.

To date, the capacity of 2.5-inch magnetic carriers ranges from 160 GB to 1.5 TB (the most common volumes: 250 GB, 320 GB, 500 GB, 750 GB and 1 TB). 3.5 "disks for desktops are more capacious and can be stored from 160 GB to 4 TB of data (the most common volumes: 320 GB, 500 GB, 1 TB, 2 TB and 3 TB).

When choosing a HDD capacity, consider one important detail - the larger the size of the hard disk, the lower the price of 1 GB of information storage. For example, a desktop hard drive for 320 GB costs 1600 rubles, 500 GB - 1650 rubles, and 1 TB - 1950 rubles. We believe: in the first case, the cost of gigabyte storage is 5 rubles (1600/320 \u003d 5), in the second - 3.3 rubles, and in the third - 1.95 rubles. Of course, such statistics does not mean that it is necessary to buy a very large disc disk, but in this example It is very clear that the purchase of a 320-gigabyte disk is inexpedient.

If you plan to use a computer mainly to solve office tasks, then you are more than enough Winchester with a capacity of 250 - 320 GB, and even less, if, of course, there is no need for storage on a computer with huge documentation archives. At the same time, as we noted above, buying a hard disk with a volume below 500 GB is unprofitable. Saving from 50 to 200 rubles, in the end you get very high cost One gigabyte storage data. In this case, this fact concerns the disks of both form factors.

Want to collect a gaming or multimedia PC to work with graphics and video, plan to download new movies and music albums on the hard drive in large quantities? Then the hard disk is better to choose a volume of at least 1 TB for desktop PC and at least 750 GB for mobile. But, of course, the final calculation of the container of the hard drive must comply with the specific needs of the user and in this case we only give recommendations.

Separately, it is worth noting the data storage systems (NAS) and have become popular multimedia players. As a rule, large disks 3.5 "are installed in such equipment, preferably with a volume of at least 2 TB. After all, these devices are focused on storing large amounts of data, and therefore the hard drives installed in them must be capacious with the lowest storage price of 1 GB of information.

Disc geometry, plate and recording density

When choosing a hard disk should not be blindly oriented only on its total capacity, according to the principle "The more, the better." There are other important characteristics, among which: record density and the number of plates used. After all, not only the volume of the hard drive, but also the speed of recording / reading data directly depends on these factors.

Let's make a little retreat and say a few words about constructive features modern storage devices on hard magnetic disks. The data record in them is carried out on aluminum or glass discs, called plates that are covered with ferromagnetic film. For writing and reading data with one of the thousands of concentric paths located on the surface of the plates, the reading heads are accomplished on the special turning brackets-positioners, sometimes called "rocker". This procedure occurs without a direct (mechanical) contact between the disk and the head (they are at a distance of about 7-10 nm from each other), which protects against possible damage and long service life of the device. Each plate has two working surfaces and is served by two heads (one per side).

To create a targeted space, the surface of the magnetic disks is divided into a plurality of annular areas, called tracks. In turn, the tracks are divided into equal segments - sectors. Because of such a ring structure, the geometry of the plates, and more precisely, their diameter affects the speed of reading and write information.

Closer to the outer edge of the track disk have a larger radius (greater length) and contain a larger number of sectors, which means that more information that can be read by a device in one turn. Therefore, on the external paths of the disk, the data transfer rate is greater, since the reading head in this area overcomes for a certain time interval is greater than on the inner tracks that are closer to the center. Thus, discs with a diameter of 3.5 inches are characterized by a higher productivity than discs that this value is 2.5 inches.

Inside the hard disk there can be several plates at once, for each of which you can write a certain maximum amount of data. In fact, this is determined by the record density, measured in gigabits per square inches (Gb / inch 2) or in gigabytes on the plate (GB). The more this value, the more information is placed on one plate of the plate, and the faster the record is recorded, as well as the subsequent reading of information arrays (regardless of whether the speed of rotation of the disks) is carried out.

The total volume of the hard drive is made up of the containers of each of the plates placed in it. For example, appeared in 2007, the first commercial accumulator with a capacity of 1000 GB (1TB) had a total of 5 plates with a density of 200 GB each. But technological progress does not stand still in place and in 2011, thanks to the improvement of perpendicular recording technology, Hitachi presented the first plate with a capacity of 1 TB, which are used everywhere in modern high-volume hard drives.

Reducing the number of plates in hard drives carries a number of important advantages:

• Reduction of data reading time;
• Reduction of energy consumption and heat dissipation;
• Improving reliability and fault tolerance;
• Reduction of mass and thickness;
• Reduced cost.

To date, the computer market at the same time there are models of hard drives, which use plates with different entry densities. This means that the hard drives of the same volume can have a completely different number of plates. If you are looking for the most effective solution, it is better to choose an HDD with the least amount of magnetic plates and high record density. But the problem is that, practically in any computer store in the descriptions of the disk characteristics, the value of the above described parameters you will not find. Moreover, this information is often absent even on the official sites of manufacturers. As a result, for ordinary ordinary users, these characteristics are far from always determining when choosing a hard disk due to their hard-to-access. However, before buying, we recommend that you find the values \u200b\u200bof these parameters, which allow you to choose the hard drive with the most advanced and modern characteristics.

Spindle rotation speed

The speed of the hard disk directly depends not only on the record density, but also on the speed of rotation of the magnetic disks placed in it. All plates that are inside the hard drive are tightly attached to its inner axis, called spindle, and rotate with it, as a whole. The faster the plate will rotate, the sooner there is a sector that should be read.

In stationary home computers, the model of hard drives that have a working frequency of rotation 5400, 5900, 7200, or 10000 revolutions per minute are used. Devices with a spindle speed of 5400 rpm, usually function quieter of its high-speed "competitors" and have less heat dissipation. Winchesters with higher revolutions, in turn, are characterized by better performance, but more energy consumption.

For a conventional office PC, there will be enough drive, in which the speed of spindle rotation is 5400 rpm. Also, such discs are well suited for installation in multimedia players or data warehouses, where not so much the rate of information transfer is played as an important role, how much reduced power consumption and heat dissipation.

In other cases, in the overwhelming majority, discs are used at the speed of rotation of the plates of 7200 rpm. This applies to both the computers of the middle and top class. The use of HDD with a rotational speed of 10,000 rpm occurs relatively rarely, as such models of hard drives are very noisy and have a sufficiently high cost of storing one gigabyte information. Moreover, in latelyUsers are increasingly preferred to use instead of productive magnetic disks, solid-state drives.

In the mobile sector, where 2.5-inch discs are reigning, the most common spindle speed is 5400 rpm. This is not surprising, as small power consumption is important for portable devices. low level Heating parts. But did not forget about the owners of productive laptops - there is a large selection of models at a speed of rotation of 7,200 rpm and even several representatives of the Velociraptor family of rotation speed of 10,000 rpm. Although the feasibility of applying the latter even in the most powerful mobile PC is under great doubt. In our opinion, if necessary, installing 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 connect to system plates Personal computers using SATA serial interface (Serial ATA). If you have a very old computer, then an option is possible using the PATA parallel interface (IDE). But note that the range of such Winchesters in stores is very much so much, as their production is almost completely discontinued.

As for the SATA interface, here 2 disks are presented here: connecting through the SATA II or SATA III bus. In the first embodiment, the maximum data transfer rate between the disk and the RAM can be 300 MB / s (tire bandwidth up to 3 Gbps), and in the second - 600 MB / s (tire capacity up to 6 Gb / c). Also, the SATA III interface is worth noting several improved power management.

In practice, for any classic hard drives "For the eyes", there is enough bandwidth of the SATA II interface. After all, even the most productive models HDD speed Reading data from the plates barely exceeds the figure of 200 MB / C. Another thing is solid-state drives, where data is stored not on magnetic plates, but in flash memory, the read speed of which is many times more and can reach more than 500 MB / c.

It should be noted that in all versions of the SATA interface, compatibility is stored at the exchange, connectors and cable protocols level. That is, the Winchester with the SATA III interface can be safely connected to the motherboard through the SATA I connector, however, the maximum drive throughput will be limited to the capabilities of an older revision and will be 150 MB / s.

Buffer memory (cache)

Buffer memory is fast intermediate memory (usually standard type RAM), which serves to level (smoothing) the difference between the speeds of reading, writing and transmitting over the data interface during disk operation. Winchester cache can be used to store the latest reading data, but not yet transmitted for processing or data that can be requested.

In the previous section, we have already noted the difference between the performance of the hard disk and throughput interface. It is this fact that is due to the need for transit storage in modern hard drives. Thus, while recording or reading data from magnetic plates, the system for its needs can use the information stored in the cache, without standing waiting.

The magnitude of the clipboard in modern hard drives performed in the form factor 2.5 "may be 8, 16, 32 or 64 MB. At the older 3.5-inch fellow, the maximum value of buffer memory reaches 128 MB. In the mobile sector, the most common disks with cache 8 and 16 MB. Among the hard drives for desktop PC are the most common buffer volumes are 32 and 64 MB.

Purely theoretically, larger cache must provide greater productivity disks. But in practice it is not always so. Exist various operations With a disc, in which the clipboard practically does not affect the performance of the hard drive. For example, it can occur with a sequential reading of data from the surface of the plates or when working with large files. In addition, algorithms that can prevent errors when working with buffer are affected on the efficiency of the cache. And here the disk with a smaller cache, but advanced algorithms of his work, may be more productive than a competitor who has a greater clipboard.

Thus, chanting for the maximum buffer memory is not worth it. Especially if the casha must be fully overpayed for the larger cache container. In addition, manufacturers try to equip their products to equip their products with the most efficient cache volume, based on the class and characteristics of certain disk models.

Other features

In conclusion, let's briefly consider some of the remaining characteristics that you can get caught in the descriptions of hard drives.

Reliability or average troubleshooting time ( MTBF) - The average duration of the hard drive to its first breakdown or the emergence of repair. It is usually measured in hours. This parameter is very important for disks used in server stations or file storages, as well as as part of RAID arrays. As a rule, specialized magnetic drives have an average operation time from 800,000 to 1,000,000 hours (for example, the Red Series discs from the company WD or the Constellation series from Seagate).

Noise level - Noise created by elements of a hard disk when it works. Measured in decibels (dB). Mostly folds out of noise that occurs when positioning heads (crackling) and noise from spindle rotation (rustling). As a rule, the smaller the speed of rotation of the spindle, the quieter works hard drive. Silent hard disk can be called if its noise level is below 26 dB.

Power consumption - important parameter for disks installed in mobile deviceswhere the big time is valued autonomous work. Also on energy consumption directly depends on the heat release of the hard drive, which is also important for the portable PC. As a rule, the level of energy consumption is indicated by the manufacturer on the disk cover, but blindly trusting these figures is not worth it. Very often they are far from reality, so if you really want to figure out the power consumption of a disk model, then it is better to look for the results of independent tests on the Internet.

Arbitrary access time - The average time for which the positioning of the reading head of the disc is performed above the arbitrary section of the magnetic plate, measured in milliseconds. A very important parameter affecting the performance of the Winchester as a whole. The less positioning time, the faster the data will be recorded or counted on the disk. It can be from 2.5 ms (in some models of server drives) to 14 ms. On average, 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 of 3.6 ms arbitrary access.

Conclusion

In conclusion, I would like to say a few words about increasing hybrid popularity magnetic drives (SSHD). Devices of this type combine the usual hard disk (HDD) and solid State Drive (SSD) of a small size, acting as an additional cache. Thus, developers are trying to use together the main advantages of two technologies - the large capacity of the magnetic plates and the speed of flash memory. At the same time, the cost of hybrid disks is much lower than that of new-fashioned SSD, and a little higher than that of ordinary HDDs.

Despite the prospects of this technology, so far sSHD drives The hard disk market shows very weakly only with a small number of models in the form factor of 2.5 inches. In this segment, Seagate exhibits the greatest activity, although competitors Western Digital. (WD) and Toshiba also presented their hybrid solutions. All this leaves the hope that the SSHD market of hard drives will develop, and we will see new models coming in the near future. similar devices Not only for mobile computers, but also for desktop PCs.

On this we finish our review, where we reviewed 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 best parameters that appropriate to them.

Published hard disk.

Also not bypassed the HDD interface, where the main features and differences were considered. sATA interface and outdated IDE. And of course not forgotten, perhaps the most important characteristic is hard disk volume.

In this material we will talk about the remaining characteristics of hard drives that are equally important than the above.

Hard disk form factor

On the this momentThe two hard disk form factor is widespread - it is 2.5 and 3.5 inches. Form factor, to a greater extent, the dimensions of hard drives are determined. By the way, in the hard drive 3.5 ", it is placed up to 5 plates of the drive, and 2.5" to 3 plates. But in modern realities, this is not an advantage, since the developers have determined for themselves that setting more than 2 plates in ordinary high-performance hard drives - Not appropriate. Although the form factor of 3.5 "does not intend to surrender at all and in terms of demand, it confidently outsources 2.5" in the desktop segment.

That is, for the desktop system, until it makes sense to acquire only 3.5 ", as among the advantages of this form factor, you can note the lower cost per gigabyte space, with a larger volume. This is achieved due to the greater, in size of the plate, which at the same recording density accommodates a larger amount of data than 2.5 ". Traditionally, 2.5 "always positioned as a form factor for laptops, more thanks to its dimensions.

There are other form factors. For example, in many portable devices, hard disks of the form factor of 1.8 "are used, but we will not stop in detail.

Hard Disk Cache Cache

Cache memory - This is a specialized RAM, which acts as an intermediate link (buffer), for storing data, which are already read from the hard disk, but have not yet been transmitted directly to processing. The presence of the buffer was caused by a significant difference in the speed between the other components of the system and the hard disk.

As such a characteristic of the HDD cache, is the volume. At the moment, hard disks with a buffer 32 and 64 MB are most popular. In fact, buying a hard disk with a large amount of cache memory, will not give a two-time increase in performance, as it may appear on the basis of classical arithmetic. Moreover, testing has shown that the advantage of hard drives with 64 MB cache is quite rare and only when performing specific tasks. Therefore, it is possible to purchase a hard disk with more volumetric cache memory, but if it goes into significant damage to the price tag, then this is not the parameter to which you want to navigate first.

Arbitrary access time

An indicator of arbitrary hard disk access characterizes the time for which the hard drive will guarantee reading the read operation anywhere in the hard disk. That is, for what period of time, the reading head will be able to get to the most remote hard disk sector. This, to greater extent, depends on the previously considered characteristic of the rotational speed of the hard disk spindle. After all, the greater the speed of rotation, the faster the head can get to the desired path. In modern hard drives, this indicator ranges from 2 to 16 ms.

The remaining HDD features

Now the following and briefly list the remaining characteristics of hard drives:

• Energy consumption - consume tight discs quite a bit. With that, often indicates the maximum power consumption, which takes place, only at intermediate stages of operation during peak boot. On average, it is 1.5-4.5 W;
• Reliability (MTBF) - the so-called time for failure;
• Data transfer rate - from the outer zone of the disk: from 60 to 114 MB / C, and from the inner - from 44.2 to 75 MB / s;
• The number of I / O operations per second (IOPS) - in modern hard drives, this indicator is about 50/100 OP. / C, with arbitrary and consistent access.

So we reviewed all the characteristics of hard drives with a small series of articles. Naturally, many parameters intersect and, to some extent, affect each other. But, on the basis of information regarding all these parameters, you can simulate a future device for yourself, and when choosing, it is clearly understood which of the models should be given the advantage in your particular case.

But such toys can turn out of old hard drives, or rather from the component of the hard disk. For example, the wheels are made from the spindle engine of the hard drive, which drives the axis with the reading head.