What types of hard drives are there?

The types of hard drives can be divided into: 1. Solid state drive (SSD), which uses flash memory particles to store; 2. Mechanical hard drive (HDD), which uses magnetic discs to store; 3. Hybrid hard drive (HHD), It is a hard disk that integrates magnetic hard disk and flash memory.

The hard drive is one of the main storage media of the computer and consists of one or more aluminum or glass discs. The disc is covered with ferromagnetic material.

1. Types

Hard drives include solid state drives (SSD disks, new hard drives), mechanical hard drives (HDD traditional hard drives), and hybrid hard drives (HHD, a new hard drive based on traditional mechanical hard drives) . SSD uses flash memory particles for storage, HDD uses magnetic discs for storage, and hybrid hard disk (HHD: Hybrid Hard Disk) is a hard drive that integrates magnetic hard disk and flash memory. The vast majority of hard drives are fixed hard drives, permanently sealed and secured within the hard drive.

2. Capacity

As the data storage of computer system, capacity is the most important parameter of hard disk.

The capacity of a hard disk is measured in megabytes (MB/MiB), gigabytes (GB/GiB) or terabytes (TB/TiB). The common conversion formula is: 1TB =1024GB, 1GB=1024MB and 1MB=1024KB. However, hard disk manufacturers usually use GB, that is, 1G = 1000MB, and the Win system still uses the word "GB" to represent the "GiB" unit (converted to 1024), so we can see it in the BIOS or when formatting the hard disk. The resulting capacity will be smaller than the manufacturer's nominal value.

The capacity index of the hard disk also includes the single disk capacity of the hard disk. The so-called single disk capacity refers to the capacity of a single hard disk platter. The larger the single disk capacity, the lower the unit cost and the shorter the average access time.

Generally speaking, the larger the hard disk capacity, the cheaper the price per byte, but there are slight exceptions for hard disks that exceed the mainstream capacity.

When we bought the hard drive, it was said to be 500G, but the actual capacity was smaller than 500G. Because the manufacturer converts according to 1MB = 1000KB, so when we buy a new hard drive, the actual usage is smaller than when we buy it.

3. Rotation speed

Rotation speed (Rotational Speed ​​or Spindle speed) is the rotation speed of the motor spindle in the hard disk, which is the maximum number of revolutions that the hard disk platter can complete in one minute. The speed of rotation is one of the important parameters that indicates the grade of the hard disk. It is one of the key factors that determines the internal transmission rate of the hard disk and directly affects the speed of the hard disk to a large extent. The faster the hard disk rotates, the faster the hard disk searches for files, and the corresponding hard disk transmission speed is also improved. The hard disk speed is expressed in revolutions per minute, and the unit is RPM. RPM is the abbreviation of Revolutions Per minute, which is revolutions per minute. The larger the RPM value, the faster the internal transfer rate, the shorter the access time, and the better the overall performance of the hard drive.

The spindle motor of the hard disk drives the platter to rotate at high speed, generating buoyancy to make the magnetic head float above the platter. To bring the sector of data to be accessed under the head, the faster the rotation speed, the shorter the waiting time. Therefore, the rotational speed determines the speed of the hard drive to a large extent.

The speeds of ordinary hard drives for home use generally include 5400rpm and 7200rpm. High-speed hard drives are also the first choice for desktop computer users; while for notebook users, 4200rpm and 5400rpm are the main ones, although some companies have released 10000rpm notebooks. Hard drives are relatively rare in the market; server users have the highest requirements for hard drive performance. SCSI hard drives used in servers basically use 10,000rpm, and even 15,000rpm, and their performance is much higher than that of household products. Higher rotational speed can shorten the average seek time and actual read and write time of the hard disk. However, as the hard disk rotation speed continues to increase, it also brings negative effects such as temperature increase, increased motor spindle wear, and increased operating noise.

4. Manufacturer

1. Seagate

Seagate was founded in 1980 and is now the world's largest manufacturer of hard drives, magnetic disks and read-write heads. Seagate is a global leader in the design, manufacture and sale of hard drives for enterprise, desktop computers, mobile devices and consumer electronics. ,

2005 merger and acquisition of Maxtor

April 2011-December 2011 After acquiring the hard drive business of Samsung, it became the largest hard drive manufacturer.

2. Western Digital

Western Digital is a world-renowned hard drive manufacturer and is now the second largest hard drive manufacturer in the world. It was founded in 1979 and is headquartered in California, USA. It has branches or offices around the world to provide storage products to users on five continents. It acquired Hitachi in March 2011.

3. Hitachi (HITACHI)

HITACHI Hitachi Group is one of the world's largest comprehensive multinational groups. It produces desktop computer hard drives and notebook hard drives. In 2002, it acquired IBM's hard disk production division. It was acquired by Western Digital in March 2011.

4. Toshiba (TOSHIBA)

Japan’s largest semiconductor manufacturer and the second largest comprehensive motor manufacturer, it is affiliated to the Mitsui Group. Mainly produces mobile storage products.

5.Samsung

The abbreviation of Samsung Group, South Korea’s largest enterprise group. It manufactures hard drives for use in desktop computers, mobile devices and consumer electronics. On April 19, 2011, Seagate officially announced the acquisition of Samsung's hard drive business for US$1.375 billion (cash and stock). On December 20, 2011, Seagate announced that it had completed the acquisition of Samsung Electronics Co., Ltd.'s hard drive business.

5. Interface types

ATA

ATA, the full name of Advanced Technology Attachment, uses a traditional 40-pin parallel port data cable to connect the motherboard and hard disk. The maximum external interface speed is 133MB/s, because the anti-interference performance of the parallel port cable is too poor, and the cable takes up space, which is not conducive to computer heat dissipation, and will be slowly replaced by SATA.

IDE

The full name is Integrated Drive Electronics, which is "electronic integrated drive", commonly known as PATA parallel port.

Advantages of RAID

1. High transmission rate. In some RAID modes, many disk drives can transmit data at the same time, and these disk drives are logically one disk drive, so using RAID can achieve several times the speed of a single disk drive. Because the speed of processors is increasing rapidly, and the data transfer rate of disk drives cannot be significantly increased, a solution is needed to resolve the contradiction between the two. 2. Higher security. Compared with ordinary disk drives, many RAID modes provide a variety of data repair functions. When a disk drive in the RAID has a serious problem and cannot be used, the data in this drive can be restored through other disk drives in the RAID. Ordinary disk drives cannot achieve this, which is the second reason for using RAID

SATA

In 2001, it was formed by several major manufacturers including Intel, APT, Dell, IBM, Seagate and Maxtor The Serial ATA Committee formally established the Serial ATA 1.0 specification. In 2002, although Serial ATA related equipment had not yet been officially launched, the Serial ATA Committee had taken the lead in establishing the Serial ATA 2.0 specification. Serial ATA uses a serial connection method. The Serial ATA bus uses embedded clock signals and has stronger error correction capabilities. Compared with the past, its biggest difference is that it can check the transmission instructions (not just data) and if found Errors are corrected automatically.

SATA Ⅱ

SATA Ⅱ is developed on the basis of SATA by chip giant Intel and hard drive giant Seagate. Its main feature is that the external transfer rate is further improved from SATA's 150MB/s. At 300MB/s, it also includes a series of technical features such as NCQ (Native Command Queuing), Port Multiplier, and Staggered Spin-up. However, not all SATA hard drives can use NCQ technology. In addition to the hard drive itself supporting NCQ, the SATA controller of the motherboard chipset is also required to support NCQ.

SATA Ⅲ

The official name is "SATARevision3.0". It is a new version of the specification released by the Serial ATA International Organization (SATA-IO) in May 2009. It mainly doubles the transmission speed. 6Gbps, while being backward compatible with the old version of the specification "SATARevision2.6" (now commonly known as SATA3Gbps), the interface and data cable have not changed. The SATA3.0 interface technical standard was proposed by Intel in the first half of 2007 and is headed by Knut Grimsrud, technical director of Intel's storage product architecture planning department. Knut Grimsrud said that the transmission rate of SATA3.0 will reach 6Gbps, which will be doubled based on SATA2.0.

SCSI

The full English name of SCSI is "Small Computer System Interface" (Small Computer System Interface). It is a completely different interface from IDE (ATA). The IDE interface is the standard for ordinary PCs. interface, and SCSI is not an interface specifically designed for hard disks. It is a high-speed data transmission technology widely used on minicomputers. The SCSI interface has the advantages of wide range of use, multi-tasking, large bandwidth, low processor occupancy, and hot-swappability. However, the higher price makes it difficult to be as popular as IDE hard drives, so SCSI hard drives are mainly used in mid- to high-end in servers and high-end workstations.

Fibre Channel

The English spelling of Fiber Channel is Fiber Channel. Like the SCSI interface, Fiber Channel was not originally an interface technology developed for hard disk planning. It was specifically designed for network systems, but it has Due to the storage system's need for speed, it was slowly used in hard disk systems. Fiber Channel hard drives were developed to improve the speed and flexibility of multi-hard drive storage systems. Its emergence has greatly improved the communication speed of multi-hard drive systems. The main features of Fiber Channel are: hot-pluggability, high-speed bandwidth, remote connection, large number of connected devices, etc.

Fiber Channel is designed for multi-hard disk system environments such as servers. It can meet the needs of high-end workstations, servers, mass storage subnetworks, and peripherals for bidirectional and serial connections through hubs, switches, and point-to-point connections. Data communication and other systems have requirements for high data transmission rates.

Classification of RAID

RAID 0, a disk array with no redundancy and no parity. Data is distributed on various disks at the same time, with no fault tolerance. The read and write speed is the fastest in RAID. However, because any disk damage will cause the entire RAID system to fail, the safety factor is actually lower than that of a single disk. It is generally used in situations that do not require high data security but high speed requirements, such as large-scale games, graphics and image editing, etc. This RAID mode requires at least 2 disks, and more disks can provide more efficient data transfer.

SAS

SAS (Serial Attached SCSI) is a new generation of SCSI technology. It is the same as the popular Serial ATA (SATA) hard disk, which uses serial technology to obtain higher transmission speeds. And improving the internal space by shortening the connecting lines. SAS is a new interface developed after the parallel SCSI interface. This interface is designed to improve the performance, availability and scalability of the storage system, and to provide compatibility with SATA hard drives.

6. Maintenance

1. Keep the computer working environment clean

The hard disk has a breathing hole with ultra-fine filter paper that is connected to the outside world. It can be used in normal environments without If the purification device is used in an indoor environment with severe dust, it will be adsorbed to the surface of the PCBA, the inside of the spindle motor and clog the breathing filter, so it must be protected from dust. In addition, humid environment and unstable voltage may cause hard disk damage.

2. Develop the habit of shutting down correctly

If the power of the hard disk is suddenly turned off while the hard disk is working, it may cause violent friction between the magnetic head and the disk and damage the hard disk. It may also cause the magnetic head to fail to reset correctly, causing Hard drive scratches. When shutting down, be sure to pay attention to whether the hard disk indicator light on the panel is still flashing. You can only shut down the computer when the hard disk indicator light stops flashing and the hard disk has finished reading and writing.

3. Move the hard disk correctly and pay attention to shockproof

When moving the hard disk, it is best to wait for more than ten seconds after shutting down the hard disk to completely stop spinning. When the hard disk is turned on, the hard disk rotates at high speed. A slight vibration may cause the disc and the read-write head to rub against each other, resulting in bad tracks on the disk or damage to the read-write head. Therefore, never move the hard drive or chassis while the computer is powered on. It is best to wait for more than ten seconds after the computer is turned off and the hard drive has completely stopped before moving the host or restarting the power supply. This can avoid damage to the hard drive caused by instantaneous power surges. You should be more careful when installing and disassembling the hard disk. It is strictly forbidden to bump the hard disk when moving and transporting it. It is best to protect it with foam or sponge packaging to minimize vibration.

Note: The so-called "anti-collision capability" or "anti-shock system" of the hard drive manufacturer refers to the anti-shock and anti-collision capabilities of the hard drive when it is not started, not when it is powered on.

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