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.Features
The general purpose of a hard drive is the type of devices for which it was originally intended.
—
For PC. Hard drives designed for use with conventional consumer computers and laptops. At the same time, the possibility of installing an internal HDD (see "Performance") directly depends on the form factor (see the relevant paragraph), while external models are not subject to such restrictions — it is enough for them to have the appropriate connection connector. Also note that almost all external hard drives are designed specifically for PCs; making server models external is not technically justified.
—
For the server. Hard drives designed for servers have increased speed and reliability, because they constantly have to receive and give large amounts of information. To ensure speed, they may provide an increased rotation speed (up to 15,000 rpm). Such drives are made only internal (see "Performance"), and, in addition to SATA, they can use other, more specific connection methods — for example,
SAS(see "Connection interfaces").
—
For game console. Specialized hard drives designed for use with game consoles. They are made only external (see "Performance"), they are intended mainly for storing games — including saves and user settings profiles. The main difference between such devices and classic external HDDs is
...precisely the optimization for working with game consoles, including the availability of special software tools for improved integration. Many of these drives are originally designed for a specific model or family of set-top boxes.Size
Rated capacity is one of the key parameters of a hard drive, which determines how much information can fit on it. For SSHD, this item indicates the capacity of only the hard drive, for RAID arrays, the total capacity of the array.
The volume of information in the modern world is constantly growing and require more and more capacious drives. So in most cases it makes sense to choose a larger disk. In fact, the question of choosing this parameter often rests only on the price: the cost of the drive directly depends on the volume.
If the question is in such a way that you need to choose a disk "smaller and cheaper, but that's enough" — it's worth evaluating the amount of information that you have to deal with and the specifics of use. For example, for an ordinary office PC, designed mainly for working with documents, an internal drive of
2 TB and even
1 TB will be more than enough, and an enthusiastic gamer will need
4 TB,
6 TB and even
8 TB will not be superfluous. If you use a disc for recording from camcorders, then you can get
a 10 TB,
12 TB,
14 TB,
16 TB,
18 TB or more HDD.
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.
Record technology
—
CMR(Conventional Magnetic Recording) is a classic method of magnetic recording, characterized by high data access speed. CMR hard drives are used in systems where it is important to provide high (as far as possible) data read/write speed. These are user computers, security video surveillance systems, etc. The main disadvantage of CMR hard drives is the high complexity of creating volume drives, which is reflected in their price. Additionally, HDDs with CMR technology are quite “gluttonous” in terms of power supply.
—
SMR(Shingled Magnetic Recording) — a promising technology for magnetic recording, which is called "tiled". SMR allows to achieve high data density, which in turn increases the capacity of memory drives and lowers their market value. SMR hard drives have slow rewriting speed, which makes such memory drives poorly suited for use in client computer systems. But they have proven themselves well when working as part of data processing centers, archives and similar systems for which low write / rewrite speed is not critical. However, some companies still produce SMR solutions for personal and even mobile systems. These HDDs use an optimized write/rewrite technology called Drive-Managed SMR (DM-SMR).
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.
Data transfer rate
The speed of data transfer between the disk and client devices is determined by the type of drive, spindle speed, memory buffer size and connection connectors. The last parameter is the most important, since it is impossible to exceed the bandwidth of a particular interface.
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.
