Type
The type to which the drive belongs. Hard drives in a broad sense again include several types of drives:
— HDD. Hard drives in the classical sense of the word are drives that record information on rotating magnetic platters. Despite the emergence of more advanced types of drives, classic HDDs still do not lose popularity due to the combination of impressive volumes and low cost. Their main disadvantages are significant weight and power consumption, as well as relatively low speed of reading and writing data.
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SSHD. Hybrid drives that combine the HDD described above and an SSD solid-state drive in one case; while the system perceives SSHD as a single device. The idea of such a combination is to increase the speed of reading and writing, while retaining the main advantage of the HDD — large volumes at a low cost. To do this, the solid state part of the SSHD acts as a high-speed clipboard between the system and the HDD; in terms of speed, such systems, although they do not reach full-fledged SSDs, are noticeably superior to traditional hard drives.
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RAID array. RAID arrays implemented as separate devices (usually external, see "Execution"). Such a device consists of several hard drives installed in one housing and combined into an array, perceived by the system as a single drive. There are several types (levels) of RAID, which differ in the way disks interact in an array and
..., accordingly, in the specifics of their application. So, in RAID 0, information is alternately written to each disk, which increases the speed of work; in RAID 1, each disk is a copy of all the others, which gives maximum fault tolerance, etc. Detailed information on RAID levels can be found in special sources. Also note here that buying a RAID array may turn out to be more convenient than assembling it from separately purchased disks: a ready-made array is initially equipped with everything you need and requires only minimal configuration. The main thing is to clarify before buying which RAID levels the selected model supports.Cache memory
The amount of internal hard drive memory. This memory is an intermediate link between the high-speed computer RAM and the relatively slow mechanics responsible for reading and writing information on disk platters. In particular, the buffer is used to store the most frequently requested data from the disk — thus, the access time to them is reduced.
Technically, the size of the buffer affects the speed of the hard drive — the larger the buffer, the faster the drive. However, this influence is rather insignificant, and at the level of human perception, a significant difference in performance is noticeable only when the buffer size of the two drives differs many times — for example,
8 MB and
64 MB.
NAND flash memory
The amount of NAND solid-state memory installed in the SSHD (see "Drive Type").
Such memory acts as a high-speed buffer between the system and the hard drive itself. Usually, the most frequently called data is stored in it, which speeds up subsequent access to them; and when writing data to a disk, this data is first stored in a buffer before being transferred to disk platters. Most modern SSHD drives carry 8 GB of solid-state memory on board — this is considered the most reasonable compromise between speed and overall cost of the device.
RPM
For drives used in a PC (see "Intended use"),
5400 rpm(normal) and
7200 rpm(high) are considered standard speeds. There are also
more specific options, including models with the ability to adjust the speed depending on the load. In server HDDs, in turn, higher speeds can be used —
10,000 rpm and even
15,000 rpm.
Plates
The number of platters provided in the design of the hard drive.
Physically, a hard disk consists of one or more platters, on which information is recorded. Several plates can be provided in order to achieve the desired volume without increasing the form factor. At the same time, it is also necessary to install an appropriate number of reading heads in such a drive, which complicates the design, reduces its reliability, and increases the cost. Therefore, manufacturers choose the number of plates based on a reasonable compromise between these points, and for selection, this parameter is more of a reference than practically significant.
Average search time
The time it takes for the hard disk mechanics to find random requested data to read. For each specific case, the search time is different, as it depends on the location of the data on the surface of the disk and the position of the read head, therefore, the average value is indicated in the characteristics of hard drives. The lower the average seek time, the faster the disk works, all other things being equal.
Operation power consumption
The amount of power consumed by the disk when reading and writing information. In fact, this is the peak power consumption, it is in these modes that the drive consumes the most energy.
HDD power consumption data is needed primarily to calculate the overall system power consumption and power supply requirements for the system. In addition, for laptops that are planned to be used often "in isolation from outlets", it is advisable to choose more economical drives.
Standby power consumption
The amount of power consumed by the disk "idle". In the on state, the disk platters rotate regardless of whether information is being written or read or not — maintaining this rotation takes the energy consumed while waiting.
The lower the power consumption while waiting, the more economical the disk is, the less energy it consumes. At the same time, we note that in fact this parameter is relevant mainly when choosing a drive for a laptop, when energy efficiency is crucial. For stationary PCs, “idle” power consumption does not play a special role, and when calculating the requirements for a power supply, it is necessary to take into account not this indicator, but the power consumption during operation (see above).
Shockproof
A parameter that determines the resistance of the hard drive to drops and shocks during operation (that is, in the on state). Shock resistance is measured in G — units of overload, 1 G corresponds to the usual force of gravity. The higher the G number, the more resistant the disc is to various kinds of concussions and the less likely it is to be damaged, say, in the event of a fall. This setting is especially important for external drives and drives used in laptops.
