The computer's hard drive is. Hard drives and SSDs. Hard drive maintenance programs

Number of I/O operations per second(English) IOPS) - for modern disks this is about 50 op./s with random access to the drive and about 100 op./sec with sequential access.

Power consumption- an important factor for mobile devices.

Impact resistance(English) G-shock rating) - the drive’s resistance to sudden pressure surges or shocks, measured in units of permissible overload in the on and off state.

Data transfer rate(English) Transfer Rate) with sequential access:

• internal disk area: from 44.2 to 74.5 MB/s;
• outer disk zone: 60.0 to 111.4 MB/s.

Buffer capacity- a buffer is an intermediate memory designed to smooth out differences in read/write speed and transfer speed over the interface. In modern disks it usually varies from 8 to 64 MB.

Noise level

Silicone washers for fastening hard drives. Reduce vibration and noise

Noise level- the noise produced by the mechanics of the drive during its operation. Indicated in decibels. Quiet drives are considered devices with a noise level of about 26 dB or lower. The noise consists of spindle rotation noise (including aerodynamic noise) and positioning noise.

To reduce noise from hard drives, the following methods are used:

Manufacturers

Initially, there was a wide variety of hard drives on the market, manufactured by many companies. Due to increased competition, rapid capacity growth requiring modern technology, and falling profit margins, most manufacturers were either acquired by competitors or switched to other types of products.

Currently, due to the promotion to the market external drives and the development of technologies such as SSD, the number of companies offering ready-made solutions has increased again.

Device

The hard drive consists of a hermetic zone and an electronics unit.

Hermozone

Disassembled Samsung HD753LJ hard drive with a capacity of 750 GB

Disassembled hard drive

The hermetic zone includes a housing made of durable alloy, disks (plates) with a magnetic coating, in some models separated by separators, as well as a head block with a positioning device, and an electric spindle drive.

Contrary to popular belief, the vast majority of devices do not have a vacuum inside the containment area. Some manufacturers make it sealed (hence the name) and fill it with purified and dried air or neutral gases, in particular nitrogen, and install a thin metal or plastic membrane to equalize the pressure. (In this case, there is a small pocket inside the hard drive case for a packet of silica gel, which absorbs water vapor remaining inside the case after it is sealed). Other manufacturers equalize the pressure through a small hole with a filter capable of trapping very small (a few micrometers) particles. However, in this case, the humidity is also equalized, and harmful gases can also penetrate. Pressure equalization is necessary to prevent deformation of the containment zone body during changes in atmospheric pressure (for example, in an airplane) and temperature, as well as when the device warms up during operation.

Dust particles that find themselves in the hermetic zone during assembly and land on the surface of the disk are carried during rotation to another filter - a dust collector.

Disks (plates), as a rule, are made of a metal alloy. Although there were attempts to make them from plastic and even glass (IBM), such plates turned out to be fragile and short-lived. Both planes of the plates, like a magnetic tape, are covered with the finest ferromagnetic dust - oxides of iron, manganese and other metals. The exact composition and application technology are a trade secret. Most budget devices contain one or two plates, but there are models with more plates.

The disks are rigidly fixed to the spindle. During operation, the spindle rotates at a speed of several thousand revolutions per minute (from 3600 to 15,000). At this speed, a powerful air flow is created near the surface of the plate, which lifts the heads and makes them float above the surface of the plate. The shape of the heads is calculated so as to ensure during operation optimal distance from the plate. Until the disks accelerate to the speed required for the heads to “take off”, parking device holds the heads in parking area. This prevents damage to the heads and the working surface of the plates. The spindle motor of the hard drive is three-phase synchronous, which ensures the stability of rotation of the magnetic disks mounted on the axis (spindle) of the motor. The motor stator contains three windings connected in a star with a tap in the middle, and the rotor is a permanent sectional magnet.

Separator (separator) is a plate made of plastic or aluminum located between the plates of magnetic disks and above the top plate of the magnetic disk. Used to equalize air flows inside the containment area.

Positioning device

Disassembled hard drive. Solenoid motor stator top plate removed

Head positioning device (servo drive, jarg. actuator) is a low-inertia solenoid motor. It consists of a fixed pair of strong neodymium permanent magnets, as well as a coil (solenoid) on a movable bracket of the head unit.

The principle of operation of the motor is as follows: the winding is located inside the stator (usually two fixed magnets), the current supplied with different strengths and polarities forces it to accurately position the bracket (rocker arm) with the heads along a radial path. The speed of operation of the positioning device determines the time it takes to search for data on the surface of the plates.

Each drive has a special zone called the parking zone, where the heads stop when the drive is turned off or is in one of the low power modes. In the parking state, the bracket (rocker arm) of the head block is in its extreme position and rests against the travel stop. During information access operations (reading/writing), one of the sources of noise is vibration due to impacts of the brackets holding the magnetic heads against the travel stops during the process of returning the heads to the zero position. To reduce noise, damping washers made of soft rubber are installed on the travel stops. You can significantly reduce the noise of a hard drive using software by changing the parameters of the acceleration and deceleration modes of the head unit. Designed for this special technology- Automatic Acoustic Management. Officially, the ability to programmatically control the noise level of a hard drive appeared in the ATA /ATAPI-6 standard (to do this, you need to change the value of the control variable), although some manufacturers have made experimental implementations before.

Electronics unit

The interface unit interfaces the hard drive electronics with the rest of the system.

The control unit is a control system that receives electrical head positioning signals and generates control actions with a voice coil drive, switching information flows from various heads, controlling the operation of all other components (for example, controlling the spindle speed), receiving and processing signals from device sensors (the sensor system may include a uniaxial accelerometer used as a shock sensor, a triaxial accelerometer used as a free fall sensor, a pressure sensor, an angular acceleration sensor, a temperature sensor).

The ROM block stores control programs for control units and digital signal processing, as well as service information of the hard drive.

Buffer memory smoothes out the speed difference between the interface part and the drive (high-speed static memory is used). Increasing the size of the buffer memory in some cases allows you to increase the speed of the drive.

The digital signal processing unit cleans the read analog signal and decodes it (extracts digital information). Various methods are used for digital processing, for example, the PRML method (Partial Response Maximum Likelihood - maximum likelihood with an incomplete response). The received signal is compared with the samples. In this case, a sample is selected that is most similar in shape and timing characteristics to the signal being decoded.

Low-level formatting

On final stage Assemblies of the device, the surfaces of the plates are formatted - tracks and sectors are formed on them. The specific method is determined by the manufacturer and/or standard, but at a minimum, each track is marked with a magnetic mark indicating its beginning.

There are utilities that can test the physical sectors of a disk and view and edit its service data to a limited extent. The specific capabilities of such utilities highly depend on the disk model and technical information, known to the author of the software of the corresponding family of models.

Geometry of magnetic disk

In order to address space, the surfaces of the disk platters are divided into tracks- concentric ring areas. Each track is divided into equal sections - sectors. CHS addressing assumes that all tracks in a given area of ​​the disk have same number sectors.

Cylinder- a set of tracks equally spaced from the center on all working surfaces of the hard disk platters. Head number specifies the working surface to be used (that is, the specific track from the cylinder), and sector number- a specific sector on the track.

To use CHS addressing you need to know geometry disk used: the total number of cylinders, heads and sectors in it. Initially, this information had to be entered manually; in the ATA-1 standard, the auto-geometry function was introduced (the Identify Drive command).

The influence of geometry on the speed of disk operations

The geometry of the hard drive affects the read-write speed. Closer to the outer edge of the disk platter, the length of the tracks increases (more sectors can be accommodated) and, accordingly, the amount of data that the device can read or write per revolution. In this case, the reading speed can vary from 50 to 30 MB/s. Knowing this feature, it is advisable to place the root partitions of operating systems here. Sector numbering starts from the outer edge of the disk from zero. In GParted, the outer edge of the disk is located on the left (in the diagram) and at the top (in the list).

Features of the geometry of hard drives with built-in controllers

Zoning

On the plates of modern hard drives, the tracks are grouped into several zones. Zoned Recording). All tracks of one zone have the same number of sectors. However, there are more sectors on the tracks of the outer zones than on the tracks of the inner ones. This allows, using a larger length of external tracks, to achieve a more uniform recording density, increasing the platter capacity with the same production technology.

Reserve sectors

To increase the service life of the disk, additional spare sectors may be present on each track. If an uncorrectable error occurs in any sector, then this sector can be replaced by a reserve one. remapping). The data stored in it can be lost or restored using ECC, and the disk capacity will remain the same. There are two reassignment tables: one is filled in at the factory, the other during operation. Zone boundaries, the number of sectors per track for each zone, and sector remapping tables are stored in the electronics ROM.

Logical geometry

As the capacity of manufactured hard drives grew, their physical geometry no longer fit into the limitations imposed by software and hardware interfaces (see: Hard drive capacity). Additionally, tracks with different numbers of sectors are not compatible with the CHS addressing method. As a result, disk controllers began to report not real, but fictitious, logical geometry, which fits into the limitations of interfaces, but does not correspond to reality. Thus, the maximum sector and head numbers for most models are 63 and 255 (the maximum possible values ​​in the BIOS INT 13h interrupt functions), and the number of cylinders is selected according to the disk capacity. The physical geometry of the disk itself cannot be obtained in normal mode operation and other parts of the system is unknown.

Data addressing

The minimum addressable data area on a hard disk is sector. The sector size is traditionally 512 bytes. In 2006, IDEMA announced a transition to a 4096 byte sector size, which is planned to be completed by 2010.

Western Digital has already announced the use of a new formatting technology called Advanced Format, and has released a series of drives using the new technology. This series includes the AARS/EARS and BPVT lines.

Before using a drive with Advanced Format technology on Windows XP, you must perform an alignment procedure using special utility. If disk partitions are created by Windows Vista, Windows 7 and Mac OS, alignment is not required.

Windows Vista, Windows 7, Windows Server 2008, and Windows Server 2008 R2 have limited support for large sector size drives.

There are 2 main ways to address sectors on a disk: cylinder-head-sector(English) cylinder-head-sector, CHS) And linear block addressing(English) linear block addressing, LBA).

C.H.S.

With this method, the sector is addressed by its physical position on the disk with 3 coordinates - cylinder number, head number And sector number. In disks larger than 528,482,304 bytes (504 MB) with built-in controllers, these coordinates no longer correspond to the physical position of the sector on the disk and are “logical coordinates” (see).

LBA

With this method, the address of data blocks on the media is specified using a logical linear address. LBA addressing began to be implemented and used in 1994 in conjunction with the EIDE (Extended IDE) standard. The need for LBA was caused, in particular, by the advent of large-capacity disks, which could not be fully exploited using old addressing schemes.

The LBA method corresponds to Sector Mapping for SCSI. The BIOS of the SCSI controller performs these tasks automatically, that is, the logical addressing method was originally characteristic of the SCSI interface.

Data recording technologies

The principle of operation of hard drives is similar to the operation of tape recorders. The working surface of the disk moves relative to the read head (for example, in the form of an inductor with a gap in the magnetic circuit). When applying AC electric current(during recording) on ​​the head coil, the alternating magnetic field that arises from the head gap acts on the ferromagnet of the disk surface and changes the direction of the domain magnetization vector depending on the signal strength. During reading, the movement of domains at the head gap leads to a change in the magnetic flux in the head magnetic circuit, which leads to the appearance of an alternating electrical signal in the coil due to the effect of electromagnetic induction.

IN Lately For reading, the magnetoresistive effect is used and magnetoresistive heads are used in disks. There's a change in them magnetic field leads to a change in resistance, depending on changes in the magnetic field strength. Such heads make it possible to increase the likelihood of reliable information reading (especially at high information recording densities).

Longitudinal recording method

Perpendicular recording hard drives have been available on the market since 2005.

Thermal magnetic recording method

Thermal magnetic recording method Heat-assisted magnetic recording, HAMR ) is currently the most promising of the existing ones; it is now actively being developed. This method uses spot heating of the disc, which allows the head to magnetize very small areas of its surface. Once the disk is cooled, the magnetization is “fixed.” As of 2009, only experimental samples were available, the recording density of which was 150 Gbit/cm². Hitachi specialists call the limit for this technology 2.3−3.1 Tbit/cm², representatives of Seagate Technology - 7.75 Tbit/cm².

Structured storage media

Structured (patterned) storage medium Bit patterned media), - promising technology data storage on a magnetic medium, which uses an array of identical magnetic cells to record data, each of which corresponds to one bit of information, in contrast to modern magnetic recording technologies, in which a bit of information is recorded on several magnetic domains.

Polymer self-assembly method

Now the latest development in the field of increasing HDD volume is the method of self-assembly of polymers (November 14, 2012).

Interface comparison

	Bandwidth, Mbit/s	Maximum cable length, m	Is a power cable required?	Number of drives per channel	Number of conductors in the cable	Other Features
UltraATA /133	1064	0,46	Yes (3.5") / No (2.5")	2	40/80	Controller+2Slave, hot swap impossible
SATA-300	3000	1	Yes	1	7	Host/Slave, hot swappable on some controllers
SATA-600	6144	no data	Yes	1	7
FireWire/400	400			63	4/6
FireWire/800	800	4.5 (at serial connection up to 72 m)	Yes/No (depending on interface and drive type)	63	9	devices are equal, hot swapping is possible
USB 2.0	480	5 (with serial connection, via hubs, up to 72 m)		127	4
USB 3.0	4800	no data	Yes/No (depending on drive type)	no data	9	Bidirectional, USB 2.0 compatible
Ultra-320 SCSI	2560	12	Yes	16	50/68	devices are equal, hot swapping is possible
SAS	3000	8	Yes	Over 16384		hot swap; it is possible to connect SATA devices to SAS controllers
eSATA	3000	2	Yes	1 (with port multiplier up to 15)	7	Host/Slave, hot swappable

History of drive progress

Hard drive market

Consequences of floods in Thailand (2011)

As a result of the flood, several industrial zones where hard drive factories are located were flooded, which, according to experts, caused a shortage of hard drives on the global market. According to Piper Jaffray, in the fourth quarter of 2011, the shortage of hard drives on the global market will be 60-80 million units with a demand volume of 180 million; as of November 9, 2011, prices for hard drives have already increased by 10 to 60%. By mid-2012, the production level and prices of hard drives returned to their previous levels.

see also

Notes

1. Reference Guide - Hard Disk Drives (English). - Overview of hard drive technology. Archived from the original on August 23, 2011. Retrieved July 28, 2009.
2. http://www.storagereview.com/guide/histEarly.html Reference Guide - Hard Disk Drives - Early Disk Drives (English)
3. IBM Archives: IBM 3340 direct access storage facility
4. Hard drive or hard drive?
5. Seagate introduced a 4 TB hard drive
6. Medalist 545XE (English) . Seagate (August 17, 1994). (inaccessible link - story) Retrieved December 8, 2008.(inaccessible link - story)
   The Medalist 545xe (Seagate ST3660A) disk specification states the following parameters: formatted volume 545.5 MB and geometry 1057 cylinders × 16 heads × 63 sectors × 512 bytes per sector = 545,513,472 bytes. However, the declared volume of 545.5 is obtained from the geometry only if it is divided by 1000 × 1000; dividing by 1024x1024 gives a value of 520.2.
   Barracuda 7200.9 320 GB PATA hard drive (ST3320833A) (English) . Seagate. - Technical Specifications tab. Archived from the original on August 23, 2011. Retrieved December 8, 2008.
   Another example: the stated volume is 320 GB and the number of available sectors is 625,142,448. However, if the number of sectors is multiplied by their size (512), the result will be 320,072,933,376. “320” from here is obtained only by dividing by 1000³, when dividing by 1024³ it turns out to be only 298.
7. Seagate Knowledge Base. Standards for measuring storage capacity (Russian)
8. http://www.hitachigst.com/hdd/support/15k147/15k147.htm
9. http://www.seagate.com/products/notebook/momentus.html (inaccessible link - story)
10. Review of Scythe Quiet Drive on thg.ru
11. Toshiba: News Release Oct 1, 2009
12. Seagate completes acquisition of Samsung's hard drive division | Seagate
13. Hard disk device. R.LAB (June 23, 2010). Archived from the original on February 3, 2012.
14. Showdown with a hard drive (getting to the bottom of hard drives), parts 1-3 / Publications / hi-Tech
15. A collection of utilities for low-level diagnostics and repair of hard drives. ???. Archived
16. Utility for diagnosing and repairing UDMA-3000 hard drives with modules for many models. ???. Archived from the original on August 23, 2011. Verified???.

Hard drives are among the key components of a PC or laptop. largely depends on the characteristics of these devices. What varieties hard drives present on the modern market? How to choose the optimal device from the point of view of solving typical user tasks?

What is a hard drive?

The hard drive is the main storage device for files on a PC or laptop. Structurally, it is a rotating magnetic plate with a reading and writing element - a head. In the slang of computer enthusiasts it is called “hard drive”, “screw”, “hard”. The specificity of the functioning of hard drives is that the reading and recording head at the same time does not contact the magnetic plate. Thanks to this, as well as a number of other design features, the device functions for a long time and can be considered as one of the most reliable means for storing information.

A hard drive is a resource on which, as a rule, system files are located, that is, those that are present in the OS structure, various applications, games. Installing software almost always involves using hard drive resources.

Most modern computer models support connecting multiple hard drives. Laptops most often have only one hard drive due to the small dimensions of the corresponding devices. Moreover, if we're talking about about type (we will look at their specifics a little later), then their maximum number is most often limited by the availability of the corresponding slots on the PC, as well as the performance characteristics of the computer.

So, the hard drive is the most important hardware component computer. Our task is to determine the criteria for the optimal selection of the appropriate device for the PC. To solve this problem, it will be useful to first examine the classification of “hard drives”.

Classification of hard drives

Let us therefore consider the types of modern hard drives available on the computer market.

Among the most popular types of devices is a computer hard drive, which corresponds to a 3.5-inch form factor. Such discs have a rotation speed of 5400 or 7200 rpm. Communication between hard drives and PCs is carried out using various interfaces. The most common are IDE and SATA.

There are hard drives adapted for servers. Their size, as a rule, is the same as in a PC, but the rotation speed of such devices is much higher - about 15,000 rotations per minute. “Hard drives” for servers are connected to the main hardware components most often via a SCSI interface, but support for serial SATA or SAS standards is possible. A server hard drive is an extremely reliable device, which is not surprising: the computers on which such drives are installed are designed to serve key areas of the digital infrastructure of companies, government organizations, and Internet providers.

These types of “hard drives” must be installed inside the system unit of a PC or server. But there are also external hard drives. They connect to one of the external ports of the computer - most often USB or FireWire. Their functionality is generally similar to that of internal type devices. The capacity of a hard drive classified as external is usually quite large - about 500-1000 GB. The fact is that this type of device is often used to move large amounts of data from one computer to another.

There are hard drives adapted for laptops. Their size is smaller than that of hard drives designed for installation in desktop computers - 2.5 inches. The speed of a laptop hard drive is most often 4200 or 5400 rpm. Such hard drives usually operate when the SATA interface is used. They are characterized by high resistance to changes in position, which is quite logical given the specific nature of using laptops.

Among the most technologically advanced types of hard drives are: solid state drives. In principle, they can be considered a separate class of devices, since there are no moving plates in their structure. Data in this type of hard drive is written to flash memory. Devices of this type have both advantages and disadvantages.

Many of the world's leading PC manufacturers are adapting their factory lines to produce devices equipped with solid-state drives. This type Hard drives are more expensive than those with rotating elements. However, in comparison with them, they are characterized by reduced energy consumption, almost complete absence noise during operation, in many cases - less weight. Regarding speed, it can be noted that a typical indicator for solid state hard disks - 300-400 MB/sec, which is very decent compared to the leading communication standards supported by modern computers.

Interfaces

The successful installation of a hard drive in a PC largely depends on the presence of the necessary interfaces in it. Let's consider the specifics of the most common communication standards in the modern computer market. This will be useful for correlating the user’s tasks and the type of “hard drive” that is optimal for solving them.

Among the most common interfaces for connecting external hard disks - USB. Moreover, this communication standard can be presented in different versions - 1, 2 and 3. The speed of the hard drive directly depends on its compatibility with the corresponding technology. Regarding the 1st version of the interface, we can say that when using it, data transfer at 12 Mbit/s is possible, the 2nd guarantees file exchange at speeds of up to 480 Mbit/s, the 3rd generation of USB interfaces provides a figure of 5 Gbit/s. If you intend to use the device not only for storing files, but also, for example, for installing games or programs, then it is best if it supports the most modern interfaces USB - in version 2, and even better in version 3.

An external computer hard drive can also be connected using the FireWire interface. It is characterized by a high data transfer speed of about 400 Mbit/s. Extremely effective when working with video files.

Let's look at the standards used when installing internal drives in PCs. Considered relatively outdated, but still popular, the interface is IDE.

It can transfer data at a speed of about 133 Mbps. Common in desktop PCs, largely due to the rather large size of the connector, which is not optimal for the structural structure of a laptop.

The SATA interface is the result of improvements to the IDE standard. Allows you to transfer data at speeds up to 300 Mb/sec. Characterized by increased immunity to interference. It is actively used in laptops - due to the relatively small size of the connector, as well as good data transfer speed.

The SCSI interface, as we noted above, is installed mainly on servers. It is also characterized by high data transfer speeds - about 320 Mb/sec. There is a modernized modification of the interface in question - SAS. Hard drives operating when it is activated can provide data exchange at a speed of about 12 Gbit/sec.

Hard drive selection criteria

The characteristics of the interfaces we discussed above can be considered significant criteria for choosing a hard disk. We also announced a number of other important parameters, such as the rotation speed of the device elements and form factor. But probably the most significant characteristic in terms of choosing the optimal device model is hard drive memory. In many ways, this parameter is subjective - many users will prefer a faster hard drive than one that can accommodate a large number of files. However, it is still the first thing that many users pay attention to.

The most important aspect of choosing a hard drive is that some of its nominal characteristics (for example, compatibility with certain interfaces) must be compatible with communication capabilities PC. It happens that the computer hard drive is incredibly technologically advanced, but the support for the corresponding standards on the PC motherboard is insufficient. Let's look at the key nuances of compatibility between hard drives and some hardware components of modern computers.

Size compatibility is important

We noted above that hard drives vary in size. It may seem that this parameter is of secondary importance. But often it turns out to be almost decisive. The fact is that installing a hard drive in a PC or in the corresponding area of ​​a laptop will be extremely difficult if the size of the drive is too small, and therefore suboptimal in terms of using the space available in the structure of the device. It will be practically impossible if the dimensions turn out to be too large - the hard drive simply will not fit into the computer.

Of course, this pattern is typical mainly for laptops, since problems with placing a hard drive in “desktop” PCs usually do not arise (largely due to the availability of various additional devices). Therefore, when planning to purchase new laptop hard drives, you need to know what the exact size of the current ones is. We noted above that “hard drives” with a 2.5-inch form factor are common in the corresponding types of computers. But you need to keep in mind that some laptop models have 1.8-inch hard drives.

Communication standards compatibility

The communication interfaces of the hard drive and motherboard PC. The main nuance here are differences in versions of data exchange standards. So, there are three varieties. It is important that the corresponding communication standard supported by the drive is also compatible with motherboard. It may happen that the user buys an expensive one that allows data exchange via modern standard SATA 3, hard drive (the price of such models can be about 10 thousand rubles), but the computer will not be able to fully support it. The PC owner can thus significantly overpay.

The same applies to the correlation between the USB standards supported by the hard drive and the PC. If the hard drive is designed to be connected via USB 3.0, but the motherboard does not support it, then the technological capabilities of the corresponding standard will also not be fully realized. Regarding the FireWire interface, we can say that when buying a hard drive that supports it (the price of the device can also be decent - about 8-10 thousand rubles), you need to make sure that the PC is, in principle, compatible with it. This communication standard is typical for laptops, but is absent on many desktop PCs. Of course, hard drives that support FireWire are usually also compatible with USB interfaces, and it is extremely unlikely that the device will be non-functional due to the lack of a FireWire port on the PC. But if the user, for example, expected to use the most obvious competitive advantage of FireWire - efficient work with video data, then he may not get the desired results from the hard drive.

Optimal volume

As we noted above, volume as the main characteristic of a device such as a hard drive is a very subjective parameter. For many users, relatively speaking, a few gigabytes of disk space are enough - for example, if they work mainly with documents. For some, a terabyte hard drive will not seem spacious enough due to the frequent placement of large volumes of multimedia content on it - videos, photos, music.

It is quite difficult to recommend the optimal storage capacity. But the concept of “more is better” is not always the best option, again from an economic point of view. You can spend money on an expensive, spacious hard drive - 1TB. A whole terabyte will thus be available - but in practice it can be used barely half. Moreover, when purchasing a less capacious but cheaper drive, the freed-up financial resources can be used to improve the performance of a PC or laptop (for example, buy additional module RAM or more powerful CPU cooler).

According to a number of IT specialists, a 500 GB hard drive is the optimal solution for most user tasks. So, on a hard drive of the appropriate size, you can place about 100-150 thousand photographs in good quality, install about 100-150 modern games. If the PC owner is not a collector of photo masterpieces or a gamer, then it is unlikely that he will use at least half of the corresponding resource. But if he, in turn, is interested in photography and games, then the opportunities that a 500 GB hard drive will give him may indeed not be enough. At the same time, this hard drive volume is considered one of the optimal ones from the point of view of typical tasks that modern users solve.

RPM speed

Another important parameter that characterizes a hard drive is the platter rotation speed. Regarding it, we can say that it is important from the point of view of the actual data transfer speed, as well as the dynamics of the operating system processing of various files. If the hard drive is used as the main one, that is, the OS is installed on it, programs and games are installed on it, then it is better if the characteristic in question is expressed in as large quantities as possible. If the user buys second hard a disk designed primarily for storing files, then in this sense the rotation speed of the platters is not the most important indicator.

The higher the value of the indicator in question, the more expensive the drive. In this sense, overpaying for higher revolutions, despite the fact that their presence is not required, may, again, turn out to be undesirable. A hard drive with a high disk rotation speed produces significantly more noise than one with a more modest rotation speed, and is also characterized by high power consumption. The optimal indicator for modern hard drives, at which it is possible effective solution most user tasks - 7200 rpm.

Cache memory

Among the significant performance indicators of a drive is cache memory. By using this resource, a hard drive can significantly speed up the procedures for performing many operations with files. The cache memory records the most frequent algorithms for requests to certain computer resources. If some data is present in the cache, then the hard drive does not need to look for it in space random access memory or among files. How larger size cache memory, the better. But the optimal value of the corresponding indicator recommended by many experts is 64 MB.

Does brand matter?

Does it make sense to choose a hard drive, all other things being equal, based on the brand? The opinions of IT experts and users on this matter are very different. This applies to both the recommendation to focus on the brand and points of view on the quality of drives produced by a particular manufacturer. Some users will characterize their Samsung-manufactured hard drive exclusively positively; reviews from other owners of a device from the Korean brand may be less enthusiastic. Some IT experts praise the Hitachi and Toshiba brands, while others do not consider them any better than their competitors. At the same time, these companies are market leaders. In any case, this fact should be considered significant. Leader status in a highly competitive market computer components doesn't come easy. This is probably due to the high quality of the goods produced.

So, if we need a hard drive for a PC or laptop, then we can focus on the following set of criteria:

Size (relevant mainly for laptops - it is undesirable for the corresponding indicator to be smaller than the slots provided for hard drives; it is unacceptable for it to be larger);

Supported standards (it is important that the technological interfaces on the hard drive are fully compatible with PC resources);

Volume (subjective, but 500 GB - optimal indicator for most user tasks);

Plate rotation speed (optimally - 7200 rpm);

Cache memory (optimally 64 MB).

It is also desirable that the hard drive be produced by a manufacturer that is a leader in the world market in the corresponding device segment.

When the computer starts, a set of firmware stored in BIOS chip, checks equipment. If everything is fine, it transfers control to the operating system boot loader. Then the OS loads and you start using the computer. At the same time, where was the operating system stored before turning on the computer? How did your essay, which you wrote all night, remain intact after the PC was turned off? Again, where is it stored?

Okay, I probably went too far and you all know very well that computer data is stored on the hard drive. However, not everyone knows what it is and how it works, and since you are here, we conclude that we would like to find out. Well, let's find out!

What is a hard drive

By tradition, let's look at the definition of a hard drive on Wikipedia:

HDD (screw, hard drive, hard magnetic disk drive, HDD, HDD, HMDD) - a random access storage device based on the principle of magnetic recording.

Used in the vast majority of computers, and also as separately connected storage devices backup copies data as file storage and so on.

Let's figure it out a little. I like the term " hard disk drive ". These five words convey the essence. HDD is a device whose purpose is to store data recorded on it for a long time. The basis of HDDs are hard (aluminum) disks with a special coating, onto which information is recorded using special heads.

I will not consider the recording process itself in detail - essentially this is the physics of the last grades of school, and I’m sure you have no desire to delve into this, and that’s not what the article is about at all.

Let us also pay attention to the phrase: “ random access “Which, roughly speaking, means that we (the computer) can read information from any section of the railway at any time.

An important fact is that the HDD memory is not volatile, that is, no matter whether the power is connected or not, the information recorded on the device will not disappear anywhere. This is an important difference between permanent computer memory and temporary memory ().

Looking at a computer hard drive in real life, you will not see either disks or heads, since all this is hidden in a sealed case (hermetic zone). Externally, the hard drive looks like this:

Why does a computer need a hard drive?

Let's look at what a HDD is in a computer, that is, what role it plays in a PC. It is clear that it stores data, but how and what. Here we highlight the following functions of the HDD:

• Storage of OS, user software and their settings;
• Storage of user files: music, videos, images, documents, etc.;
• Using part of the hard drive capacity to store data that does not fit in RAM (swap file) or storing the contents of RAM while using sleep mode;

As you can see, the computer hard drive is not just a dump of photos, music and videos. The entire operating system is stored on it, and in addition, the hard drive helps cope with the load on the RAM, taking on some of its functions.

What does a hard drive consist of?

We partially mentioned the components of a hard drive, now we will look at this in more detail. So, the main components of the HDD:

• Frame — protects hard drive mechanisms from dust and moisture. As a rule, it is sealed so that moisture and dust do not get inside;
• Discs (pancakes) - plates made of a certain metal alloy, coated on both sides, on which data is recorded. The number of plates can be different - from one (in budget options), up to several;
• Engine — on the spindle of which the pancakes are fixed;
• Head block - a design of interconnected levers (rocker arms) and heads. The part of the hard drive that reads and writes information to it. For one pancake, a pair of heads is used, since both the upper and lower parts are working;
• Positioning device (actuator ) - a mechanism that drives the head block. Consists of a pair of permanent neodymium magnets and a coil located at the end of the head block;
• Controller — electronic chip work manager HDD;
• Parking zone - a place inside the hard drive next to the disks or on their inner part, where the heads are lowered (parked) during downtime, so as not to damage the working surface of the pancakes.

This is so simple hard device disk. It was formed many years ago, and no fundamental changes have been made to it for a long time. And we move on.

How does a hard drive work?

After power is supplied to the HDD, the motor, on the spindle of which the pancakes are attached, begins to spin up. Having reached the speed at which a constant flow of air is formed at the surface of the disks, the heads begin to move.

This sequence (first the disks spin up, and then the heads start working) is necessary so that, due to the resulting air flow, the heads float above the plates. Yes, they never touch the surface of the disks, otherwise the latter would be instantly damaged. However, the distance from the surface of the magnetic plates to the heads is so small (~10 nm) that you cannot see it with the naked eye.

After startup, first of all, service information about state of rigid disk and others necessary information about him, located on the so-called zero track. Only then does work with the data begin.

Information on a computer's hard drive is recorded on tracks, which, in turn, are divided into sectors (like a pizza cut into pieces). To write files, several sectors are combined into a cluster, which is the smallest place where a file can be written.

In addition to this “horizontal” disk partition, there is also a conventional “vertical” partition. Since all the heads are combined, they are always positioned above the same track number, each above its own disk. Thus, during HDD operation, the heads seem to draw a cylinder:

While the HDD is running, it essentially performs two commands: read and write. When it is necessary to execute a write command, the area on the disk where it will be performed is calculated, then the heads are positioned and, in fact, the command is executed. The result is then checked. In addition to writing data directly to the disk, the information also ends up in its cache.

If the controller receives a read command, it first checks whether the required information is in the cache. If it is not there, the coordinates for positioning the heads are calculated again, then the heads are positioned and the data is read.

After completion of work, when the power to the hard drive disappears, the heads are automatically parked in the parking zone.

This is basically how a computer hard drive works. In reality, everything is much more complicated, but the average user most likely does not need such details, so let’s finish this section and move on.

Types of hard drives and their manufacturers

Today, there are actually three main hard drive manufacturers on the market: Western Digital (WD), Toshiba, Seagate. They fully cover the demand for devices of all types and requirements. The rest of the companies either went bankrupt, were absorbed by one of the main three, or were repurposed.

If we talk about the types of HDD, they can be divided as follows:

1. For laptops, the main parameter is the device size of 2.5 inches. This allows them to be compactly placed in the laptop body;
2. For PC - in this case it is also possible to use 2.5" hard drives, but as a rule, 3.5" are used;
3. External hard disks are devices that are separately connected to a PC/laptop, most often serving as file storage.

There is also a special type of hard drive - for servers. They are identical to regular PC ones, but may differ in connection interfaces and greater performance.

All other divisions of HDD into types come from their characteristics, so let’s consider them.

Hard drive specifications

So, the main characteristics of a computer hard drive:

• Volume — an indicator of the maximum possible amount of data that can be stored on the disk. The first thing they usually look at when choosing a HDD. This figure can reach 10 TB, although for a home PC they often choose 500 GB - 1 TB;
• Form factor — size of the hard disk. The most common are 3.5 and 2.5 inches. As mentioned above, 2.5″ in most cases are installed in laptops. They are also used in external HDDs. 3.5″ is installed in PCs and servers. The form factor also affects the volume, since a larger disk can fit more data;
• Spindle speed — at what speed do the pancakes rotate? The most common are 4200, 5400, 7200 and 10000 rpm. This characteristic directly affects the performance, as well as the price of the device. The higher the speed, the greater both values;
• Interface — method (connector type) of connecting the HDD to the computer. The most popular interface for internal hard drives today is SATA (older computers used IDE). External hard drives are usually connected via USB or FireWire. In addition to those listed, there are also such interfaces as SCSI, SAS;
• Buffer volume (cache memory) - a type of fast memory (like RAM) installed on the hard drive controller, designed for temporary storage of data that is most often accessed. The buffer size can be 16, 32 or 64 MB;
• Random access time — the time during which the HDD is guaranteed to write or read from any part of the disk. Ranges from 3 to 15 ms;

In addition to the above characteristics, you can also find such indicators as:

HDD(HDD, SCREW, WINCHESTER) is an information storage device in a personal computer. Hard drive – designed for storing and transmitting information. A hard drive stores data on the magnetic surface of the disk. Information is recorded and retrieved using magnetic heads. A hard drive can contain several platters called disks. The motor that rotates the disk turns on when power is applied to the disk and remains turned on until the power is removed. The motor rotates at a constant speed, measured in revolutions per minute (rpm). Data is organized on a disk in cylinders, tracks, and sectors. Cylinders are concentric tracks on disks, located one above the other. The track is then divided into sectors. The disk has a magnetic layer on each side. Each pair of heads is mounted, as it were, on a “fork” that clasps each disk. This “fork” moves above the surface of the disk using a separate servo motor (and not a stepper, as is often mistakenly thought - a stepper motor does not allow you to move quickly above the surface). All hard drives have spare sectors that are used by its management circuitry if bad sectors are detected on the drive.

Hard drive device:

Hard drive interfaces

A storage interface is a set of electronics that ensures the exchange of information between the device controller (cache buffer) and the computer. An interface is the way the hard drive and computer motherboard interact. It is a set special lines and a special protocol (a set of data transfer rules). That is, purely physically, it is a cable (cable, wire), on both sides of which there are inputs, and on the hard drive and motherboard there are special ports (places where the cable is connected). Thus, the concept of interface includes connection cable and the ports located on the devices it connects.

IDE- translated from English “Integrated Drive Electronics”, which literally means “built-in controller”. It was only later that IDE began to be called an interface for data transfer, since the controller (located in the device, usually in hard drives and optical drives) and the motherboard had to be connected with something. It (IDE) is also called ATA (Advanced Technology Attachment), it turns out something like “Advanced Connection Technology”.

What can I say, although the IDE was very slow (the data transfer bandwidth ranged from 100 to 133 megabytes per second in different versions of the IDE - and even then purely theoretically, in practice it was much less), but it allowed you to simultaneously connect two devices to the motherboard at once , using one loop.

Moreover, in the case of connecting two devices at once, the line capacity was divided in half. However, this is far from the only drawback of the IDE. The wire itself, as can be seen from the figure, is quite wide and, when connected, will take up the lion's share of the free space in the system unit, which will negatively affect the cooling of the entire system as a whole. All in all IDE is already outdated morally and physically, for this reason the IDE connector is no longer found on many modern motherboards, although until recently they were still installed (in the amount of 1 piece) on budget motherboards and on some boards in the mid-price segment.

The next interface, no less popular than the IDE in its time, is SATA (Serial ATA), a characteristic feature of which is serial data transmission. It is worth noting that at the time of writing this article, it is the most widespread for use in PCs.

Interfaces SATA, SATA 2(II), SATA 3 (III)

In 2002, the first hard drives appeared, with a progressive interface at that time SATA . The maximum data transfer speed of which was 150 MB/s.

If we talk about the advantages, the first thing that catches your eye is the replacement 80-wire loop (Fig. 1), to a seven-core SATA cable (Fig. 3), which is much more resistant to interference, which made it possible to increase the standard cable length from 46 cm to 1 m. Also, appropriate SATA connectors(Fig. 4), which are several times more compact than the connectors of the previous IDE standard. This made it possible to place more connectors on the motherboard; now on new motherboards you can find more than 6 SATA connectors, versus the traditional 2-3 IDE in older motherboards oriented to this standard.

Next, the SATA II standard appeared, data transfer speeds reached 300 MB/s. This standard has acquired many advantages, among them: Native Command Queuing technology (it is this technology that made it possible to achieve a speed of 300 MB/s), hot-plugging disks, executing several commands in one transaction, and others.

Well, in 2009 the interface was introduced SATA 3 . This standard provides for data transfer at speeds 600 MB/s (for hard drives, “oh” how redundant).

Interface improvements can include more efficient power management and, of course, increased speed.

It should be noted that SATA, SATA II and SATA III are completely compatible.

• 1956 - IBM 350 hard drive included in the first serial computer IBM 305 RAMAC. The drive occupied a box the size of a large refrigerator and weighed 971 kg, and the total memory capacity of 50 thin disks covered with pure iron with a diameter of 610 mm rotating in it was about 5 million 6-bit bytes.
• 1980 - the first 5.25-inch Winchester, Shugart ST-506, 5 MB.
• 1981 - 5.25-inch Shugart ST-412, 10 MB.
• 1986 - SCSI, ATA standards.
• 1990 - maximum capacity 320 MB.
• 1995 - maximum capacity 2 GB.
• 1997 - maximum capacity 10 GB.
• 1998 - UDMA/33 and ATAPI standards.
• 1999 - IBM releases Microdrive with capacities of 170 and 340 MB.
• 2000 - IBM releases Microdrive with capacities of 500 MB and 1 GB.
• 2002 - ATA/ATAPI-6 standard and drives with a capacity of over 137 GB.
• 2003 - the appearance of SATA.
• 2003 - Hitachi releases Microdrive with a capacity of 2 GB.
• 2004 - Seagate releases ST1 - an analogue of Microdrive with a capacity of 2.5 and 5 GB.
• 2005 - maximum capacity 500 GB.
• 2005 - Serial ATA 3G standard.
• 2005 - SAS appeared.
• 2005 - Seagate releases ST1 - an analogue of Microdrive with a capacity of 8 GB.
• 2006 - application of the perpendicular recording method in commercial drives.
• 2006 - the appearance of the first “hybrid” hard drives containing a flash memory unit.
• 2006 - Seagate releases ST1 - an analogue of the Microdrive with a capacity of 12 GB.
• 2007 - Hitachi introduces the first commercial drive with a capacity of 1 TB.
• 2009 - based on 500 GB platters from Western Digital, then Seagate Technology LLC released models with a capacity of 2 TB.
• 2009 - Samsung released the first hard drives with USB 2.0 interface
• 2009 - Western Digital announced the creation of 2.5-inch HDDs with a capacity of 1 TB
• 2009 - the emergence of the SATA 3.0 standard.
• 2010 - Seagate releases a 3 TB hard drive.
• 2010 - Samsung releases a hard drive with platters with a recording density of 667 GB on one platter
• 2011 - Western Digital released the first disk on 750 GB platters.

Right? Which manufacturer should you prefer? How big should a hard drive be and why is everything not visible on my system? disk space? Do you know such important characteristics of a hard drive as: form factor, cache, spindle speed, linear read speed, hard drive access time? How to check the hard drive and? What is an SSD and why is it faster than a simple HDD hard drive, but there is also one? ? Why is it better to buy two drives for good performance of a new computer: HDD and SSD? We will answer all these questions in our article.

Hello friends, choosing a hard drive is not difficult at all, but optical drive even easier, but we will touch on this issue at the end of the article.

Disk types

Desktop personal computers (PCs) and laptops use hard disk drives (HDDs) and modern solid-state drives (SSDs) based on memory chips.

HDD(English HDD - Hard Disk Drive) - an electronic-mechanical device designed to store information on it. Has a large volume, but low speed and are used both to install the operating system and store user files.

The hard drive is made of aluminum or glass plates coated with a ferromagnetic layer and is a device operating on the principle of magnetic recording. When working inside a hard drive, everything is in motion. Magnetic heads that write, read, and erase information hover above the surface of the magnetic platters of the hard drive at a height of 10-12 nm and never touch their surface, as they are easily damaged. HDD has long been obsolete and in the future it will be completely replaced by SSD.

SSD - solid state drive(SSD, solid-state drive) is a non-mechanical storage device created on the basis of memory chips similar to RAM or flash memory. SSDs are much more expensive than HDDs and have several times smaller volume, but high speed and are used to install the operating system and some programs to increase the speed of the PC. As you already understand, there is practically no mechanics inside the SSD. SSD is almost 5 times faster than HDD.

SSHD. There are also hybrid drives SSHDs, which have both magnetic platters for storing data and a small amount of solid-state memory for increased speed. But they have not yet taken root, since they are quite expensive and at the same time have little fast memory. The best option is to install separate HDD and SSD drives.

Form factor

The form factor is called hard size drive in inches. Basic hard dimensions disks:

2.5"" – HDD drives for laptops and SSDs.

3.5"" – HDD drives and hybrid drives for desktop PCs.

For laptops, only 2.5" HDDs and SSDs are used.

For stationary PCs, 3.5" HDDs are used, and 2.5" SSDs are installed in the case using a special mount, which sometimes comes with it, but most often you will have to purchase it additionally. Read our article on solid state SSD drives, all the details are there.

Please note that screws for fastening a disk in a PC case are rarely included with the disk, and if you don’t have them and the case does not have screwless fastenings, then ask the seller for 4 pieces, usually they have plenty of them.

Interface

An interface is a combination of data exchange technology (standard) and the corresponding connector for connection.

IDE– an outdated parallel data transfer interface, used a wide 40 or 80 pin connector and a corresponding cable for connection. Data transfer speed up to 133 Mb/s. Disks with an IDE interface are practically no longer produced and are much more expensive.

A drive with an IDE interface can only be considered for connecting to a motherboard that does not have a newer type of connector (SATA), but in most cases it is more advisable to purchase a more modern hard drive (SATA) and connect it to old board, it will be cheaper and can later be moved to a new computer.

The only drawback is that it may not always be possible to install an operating system (OS) on a disk connected through such a controller, since drivers for the controller are installed after the system is installed. But such a disk can be used as file storage.

SATA– the first version of the high-speed serial interface, uses a thin pin connector and a corresponding cable for connection. Data transfer speed up to 1.5 Gb/s. This version of the interface was used on the first 2.5 and 3.5" HDDs and such drives are no longer available, but are compatible with newer versions (SATA 2 and SATA 3) and can be connected to a motherboard with a connector of any of these versions.

SATA 2– the second version of the high-speed serial interface, uses the same connector and cable as the SATA first version. Data transfer speed up to 3 Gb/s. This version of the interface is still used on 2.5 and 3.5" HDDs and older 2.5" SSD models. It is compatible with both older (SATA) and newer (SATA 3) versions of the interface and can be connected to a motherboard with a connector of any of these versions.

SATA 3– the third version of the high-speed serial interface. Data transfer speed up to 6 Gb/s. This version of the interface is used on modern 2.5 and 3.5" HDDs and 2.5" SSDs. It is compatible with older (SATA and SATA2) versions of the interface and can be connected to a motherboard with a connector of any of these versions.

Please note that cables from older versions of the interface (SATA and SATA 2) are not suitable for SATA 3., since they do not have high enough frequency characteristics. SATA 3 type cables are thicker and are usually black. They come bundled with motherboards that have SATA 3 connectors, but they can also be purchased separately.

It should be noted that the speed of the interface, in any case, significantly exceeds the capabilities of any modern hard drive, and for a drive with a SATA 3 interface, the first version of the SATA connector on the motherboard may be sufficient. However, in practice it happens differently, so it is still recommended that the version of the SATA interface of the motherboard be no lower than the SATA version hard interface disk. Especially it concerns fast SSD drives that have a SATA 3 interface, which should preferably be connected to the same SATA 3 connectors on the motherboard, otherwise the drive may not work full speed(up to 30% slower).

The first SSD drives had a SATA2 interface and they can still be found on sale, but they, as a rule, are not very fast.

Power connectors

In addition to differences in interface types (IDE and SATA), old and new drives also differ in power connectors.

IDE drives had a 4-pin Molex power connector.

Transitional drive models with a SATA interface, in order to be compatible with older power supplies, had two power connectors: the old 4-pin Molex and the new 15-pin SATA power connector.

However, they usually had a warning note that you should not connect power to both connectors at the same time, but some users managed to do this.

All modern wheels with a SATA interface have a 15-pin power connector of the SATA standard, but if the power supply of an old PC does not have such a connector, they can be connected through a special adapter from a 4-pin Molex connector.

By the way, the wire for data transmission is usually called an interface cable, and for connecting the power supply - a power cable.

Capacity

Modern HDDs for PCs (3.5"") have a capacity (volume) of 500 to 3000 Gigabytes (3 Terabytes).

HDD drives for laptops (2.5"") have capacities from 320 to 1000 GB (1 TB).

Fast solid state drives (2.5"") have a capacity of 60-240 GB.

For a modern home PC, the standard today is a 1 TB HDD, which will allow you to store about 700 movies or 5,000 songs in normal quality, or 290,000 photos in high quality, or 100 modern games (usually in various combinations).

For a simple office PC, a minimum volume of 320 GB will be sufficient.

For a laptop, if it is not used to store multimedia or archive data, the optimal disk size is 500 GB, but 320 is possible. If it is used as the main home PC, then it is better to look at a disk with a capacity of 750-1000 GB.

For professional use or a serious hobby, you may need a 2-3 TB hard drive, or maybe several such drives. Just keep in mind that if the BIOS of your motherboard does not support UEFI, then when installing the OS on a 3 GB disk, the system will not see its entire capacity; about 700 GB will remain unused.

SSD drives are not used for storing information, as they have small volumes and high cost. They are used only to install the system and some programs to improve PC performance. An SSD disk with a capacity of 60 GB is enough to install Windows 7 or 8, but it is still advisable to purchase an SSD with a capacity of about 120 GB, since, firstly, Windows tends to “grow”, and secondly, you may want to install some powerful software on this disk. program or toy and thirdly, such a volume is not promising. A 240 GB SSD is cool, but it’s still expensive and basically unnecessary.

When choosing a disk, keep in mind that it is not a reliable data storage and it is recommended to duplicate it on an external disk, otherwise you risk losing everything. If you plan to follow this advice, keep in mind that you will need to purchase an external drive of similar capacity. For example, to create copies of files from 2 home PCs (or a PC and a laptop) with 500 and 1000 GB drives, you will need an external drive with a capacity of 1500 GB. If you buy a 3TB drive for your PC, how much more will you need to spend on a similar external drive?! Better buy 2 disks of 1 TB each.

Spindle speed

The bulk of modern 2.5 and 3.5" HDDs have a spindle speed of 5400 or 7200 RPM. In general, the higher the spindle speed, the higher the speed of the disk.

Most 2.5" HDDs have a spindle speed of 5400 RPM, in principle this is normal, since the noise, heating and consumption of such a disk in a laptop will be less.

Most 3.5" HDDs have a spindle speed of 7200 RPM, but there are models with a spindle speed of 5400 RPM. I would not recommend taking the latter, since such a solution seems dubious for a normal high-quality drive for a PC and they work a little slower.

There are also fast HDDs 3.5"" with a spindle speed of 10000-15000 RPM (for example, the WD Raptor series), but they are quite expensive (from $200 for 1 TB), and are only 30% faster. In addition, they are also quite noisy. It’s better to buy a 128 GB SSD and a 1 TB HDD for this money.

The SSD does not have any spindle, since it consists of memory chips, so there can be no talk about its rotation speed.

Buffer size

The buffer size is the volume of the cache, made in the form of a memory chip on the electronic board of the hard drive controller and designed to speed up its operation. The larger the cache memory, the higher the disk speed.

Old hard drives had a buffer capacity of 8-16 MB.

Modern HDDs have 32-64 MB of cache memory.

Basically the difference is in speed identical hard disks with 32 and 64 MB of cache memory are insignificant (less than 5%). But there is no point in purchasing a hard drive with a buffer size of less than 32 MB.

The most modern and expensive hard drives have 128 MB of cache, but they are not yet very common.

Linear reading speed

Linear read speed means the speed of continuous reading of data from the surface of platters (HDD) or memory chips (SSD) and is the main characteristic that reflects the real speed of the disk. It is measured in megabytes per second (Mb/s).

Old HDD drives with an IDE interface had an average linear read speed of 40 to 70 MB/s.

Modern HDD drives with a SATA interface have an average linear read speed of 100 to 140 MB/s.

SSD drives have an average linear read speed of 160 to 560 MB/s.

The linear reading 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. Basically, all HDDs of the same generation have a similar recording density, so a higher speed speaks primarily about the quality of the mechanics. At the same time, an HDD with better mechanics does not cost much more. The main thing here is to be able to choose the right disk model, which is complicated by the fact that sellers rarely indicate their speed parameters. You have to look for this information yourself.

The linear reading speed of SSD disks depends on the speed of the memory chips. But, unlike HDDs, SSD drives with faster memory are much more expensive. Choosing an SSD drive model is much easier, since sellers always indicate their speed characteristics.

For modern HDD drives, a good indicator is average speed linear reading 120 MB/s, for SSD drives – 450 MB/s.

There is also such a parameter as linear write speed, which accordingly reflects the write speed to the disk and is also measured in MB/s. For HDD drives, the write speed is usually lower than the read speed and is not taken into account when choosing a drive. But for SSD drives, the write speed can be the same as the read speed or less, and you need to pay attention to this. It is desirable that the SSD drive has the same write and read speed, for example 450/450 MB/s.

Access time

Access time means the speed at which the disk finds the required file after the operating system or any program accesses it. This time is measured in milliseconds (ms). This setting has big influence on disk performance when working with small files and not so much when working with large ones.

HDD drives have access times from 12 to 18 ms. A good indicator is an access time of 13-14 ms, which indirectly indicates the quality (accuracy) of the disk mechanics.

SSD drives have an access time of about 0.1-0.2 ms, which is 100 times faster than HDD drives! Therefore, you can ignore this parameter when choosing an SSD drive and it is usually not indicated by sellers in price lists.

Manufacturers

The main manufacturers of HDD drives are:

Fujitsu- a Japanese company previously famous high quality of its products, is currently represented by a small number of models and is not very popular, but has a very affordable pricing policy.

Hitachi– the Japanese company, both previously and now, is distinguished by the stable quality of hard drives, since it introduces only proven reliable technologies, therefore the model range of this company is updated somewhat more slowly than that of its competitors. When purchasing a Hitachi hard drive, you can't go wrong, getting good quality at an affordable price.

Samsung– this Korean company entered the hard drive market later than others and their quality at that time left much to be desired. Samsung drives were made in cheap cases, overheated and quickly failed. Today, Samsung, in my opinion, has surpassed all its competitors and produces the fastest and highest quality HDD drives. Their price may be a little higher than the competition, but it's worth it.

Seagate is an American company, a pioneer in the field of technologies used in hard drives. It was once famous for its advanced solutions and the quality of its discs. Now the quality of this company's hard drives, unfortunately, leaves much to be desired. I do not recommend purchasing them.

Toshiba is a Japanese company about which you can say everything the same as about Fujitsu - it was also famous for its high quality, but is now represented by a small number of models on our market. In this regard, problems may arise in the service of such manufacturers.

Western Digital (WD) is an American company specializing in the production of hard drives. Its disks have always been considered more reliable. For example, they used better bearings than their competitors, but because of this they were always noisier. Like Hitachi, WD drives have always had more or less stable workmanship. But recently, the drives of this company do not stand out with outstanding characteristics, like Samsung, for example. I would position them between Hitachi, which is stable in quality, and Seagate, which has slipped into consumer goods.

In general, I would advise choosing between Samsung and Hitachi, as they are the highest quality, fastest and most stable.

SSD Manufacturers

With choice SSD manufacturer disks the situation is somewhat different. Since they are made up of memory chips, they are manufactured by RAM companies.

As reputable manufacturers, I would recommend the following: Corsair, Crucial, Intel, Kingston, OCZ, Samsung, SanDisk, Toshiba, Transcend.

It is better not to purchase SSDs from well-known Chinese brands, such as: A-Data, Apacer, Silicon Power.

Price

As for HDD drives, their price depends more on their volume. The dependence on the brand, model and even quality is not so significant (5-10%), since buyers rarely pay attention to such points. Accordingly, saving on a hard drive is not particularly advisable. Just choose the desired volume, good manufacturer and check technical specifications such as linear read speed and access time. I will not give prices for HDD drives, since pricing in this segment is not adequate and depends more on marketing gimmicks. Prices for them can fluctuate 2-3 times from year to year, both towards cheaper and higher prices. A similar situation I described it in an article about RAM. For example, after the flood in Taiwan in 2011, prices for hard drives soared by an average of 2.5 times, and there was another wave of financial crisis, etc., which is why their prices have not yet returned to levels adequate to technological progress level.

Purely theoretically HDD parameters You can find out the disk by the model number on the manufacturer's website, but in practice I rarely succeeded, since it is quite difficult to find and understand these parameters on the manufacturer's website. But there is a much simpler way.

There is a fairly popular program for testing the speed (and some other parameters) of a hard drive - HDTune. The manufacturer's website has a paid (with a limited trial period) and a free version of this program.

http://www.hdtune.com/

But we don’t need it to select a disk. We are only interested in the results of tests in this program made by other users.

HDTune allows you to determine two main parameters - linear read speed and random access time.

In addition, by the very nature of the graph, you can determine the quality of the disk mechanics.

Here is an example of a disc with conventional mechanics

But with very high quality and accurate

Notice the difference? If the disk has good mechanics, then in addition to its speed parameters, such as linear reading speed and access time, the graph linear speed will have a beautiful, cyclically repeating shape, and the points for measuring random access time will be located quite densely.

In order to find test results for the drive you are interested in, enter its model number in Google image search. Now almost all sellers indicate the model number in the price list, previously there were problems with this and you had to go to a store or warehouse to look at the disc live, or pester sellers by phone, which for some reason they really didn’t like)

Find at least 2-3 similar pictures to ensure the objectivity of the tests performed. Please make sure that the picture shows exactly the correct model.

Optical drive

We define the interface: IDE - for old PCs without SATA connectors or SATA - for all new PCs. If you can't find an IDE drive for your old PC, then you will need to purchase a SATA drive and a PCI-SATA controller.

Determine which drive you need: DVD-RW (also called DVD Super Multi) or Blu-Ray (a more expensive drive for discs of the same format). If you don’t have Blu-Ray discs and don’t know why you need it, then you don’t need such a drive).

We choose popular manufacturers: ASUS, LG, Samsung and choose the cheapest available model, they will be practically no different. If you like to play it safe, you can choose the most expensive model, the difference in price will be negligible (no more than $5).

You can also purchase a drive from such manufacturers as: BENQ, HP, Lite-On, Pioneer, which may have special modes recordings and proprietary software, if you know why this is needed. Regular users This is not needed, but it may add problems during warranty service.

What you should pay attention to is the color. It comes in black, silver and white (already rare). This is important if you want the drive to fit harmoniously into the design of your PC case. If your PC case is black or silver, then black will be more suitable. In addition, the black drive panel is made of black plastic, while the silver one is always painted and the paint can wear off during use.

A DVD drive costs $20-30. The optimal price is $25.

The cheapest Blu-Ray drive costs $65. The optimal price is $75-85.

That's all, friends. We really hope that we helped you choose a hard drive for your computer!