Solid State Drive (SSD) and IDE FLASH DISK are composed of control unit and storage unit (FLASH chip). In short, it is a hard disk made of solid-state electronic storage chip array. The interface specification, definition, function and use method of SSD are the same as those of ordinary hard disk, and the product shape and size are also the same as those of ordinary hard disk. Its chip has a wide operating temperature range (- 40~85 ℃). At present, it is widely used in military, vehicle, industrial control, video monitoring, network monitoring, network terminal, power, medical, aviation, navigation equipment and other fields. Although the cost is high at present, it is also gradually popularized in the DIY market. Due to the difference between SSD technology and traditional HDD technology, many emerging memory manufacturers have emerged. Manufacturers only need to purchase NAND memory and cooperate with appropriate control chips to manufacture solid state drives. The new generation of SSDs generally use SATA-2 and SATA-3 interfaces.

classification

There are two kinds of storage media for SSDs, one is flash memory (FLASH chip) as the storage media, and the other is DRAM as the storage media.

Solid state hard disk based on flash memory

Flash based solid state disk (IDE FLASH DISK, Serial ATA Flash Disk): FLASH chip is used as the storage medium, which is also what we usually call SSD. Its appearance can be made into a variety of shapes, such as notebook hard disk, micro hard disk, memory card, U disk, etc. The biggest advantage of this SSD SSD is that it can be moved, and the data protection is not controlled by the power supply. It can adapt to various environments, but its service life is not high, and it is suitable for individual users. In flash memory based SSDs, storage cells are divided into two categories: SLC (Single Layer Cell Single Layer Cell) and MLC (Multi Level Cell Multi Layer Cell Multi Layer Cell). SLC is characterized by high cost, small capacity and fast speed, while MLC is characterized by large capacity, low cost and slow speed. Each unit of MLC is 2 bits, which is twice as much as SLC. However, due to the large amount of data stored in each MLC storage unit and its relatively complex structure, the probability of errors will increase, and error correction must be carried out. This action results in its performance greatly lagging behind that of SLC flash memory with simple structure. In addition, SLC flash memory has the advantage that the number of replications is up to 100000, 10 times higher than MLC flash memory. In addition, in order to ensure the life of MLC, the control chip checks and intelligent wear balance technology algorithm, so that the number of writes to each storage unit can be evenly distributed, reaching 1 million hours of failure interval (MTBF).

DRAM based solid state disk

DRAM based solid state disk: DRAM is used as the storage medium, and its application scope is narrow at present. It emulates the design of traditional hard disks, can be set and managed by file system tools of most operating systems, and provides industrial standard PCI and FC interfaces for connecting hosts or servers. The application mode can be divided into SSD hard disk and SSD hard disk array. It is a high-performance memory and has a long service life. The disadvantage is that it needs an independent power supply to protect data security.

Interface Type

The mainstream interface types of SSD include:

SATA interface: SATA SATAII SATA3.0

PATA (IDE interface): IDE44PIN IDE40PIN

PCI-E interface: mSATA PCIE (IDE) PCIE (SATA) ZIF: ZIF interface, etc