A disk array is a system that makes several towers drives as a whole, and the entire disk array is managed by an array controller. The full name of the array card is that the disk array card is used for RAID (inexpensive Redundant array of disks).
Redundant disk array raid (redundant array of independent disks) technology was proposed by the University of California, Berkeley, in 1987, originally designed to combine small, inexpensive disks to replace large, expensive disks to reduce the cost of mass data storage ( RAID is called Dundant array of Inexpensive disks cheap disk array), but also want to use redundant information, so that the failure of the disk will not make access to data loss, thereby developing a level of data protection technology.
Working principle and characteristics
The basic structural feature of RAID is the combination (Striping), which bundles 2 or more physical disks into groups to form a separate logical disk. A combination set (Striping set) refers to tying a physical disk group together. When multiple disk drives are leveraged, the combination provides a better performance boost than a single physical disk drive.
The data is written as a block (Chunks) in the combo set, and the size of the block is a fixed value that was selected before the bundle process was implemented. The relationship between the block size and the size of the average I/O requirement determines the characteristics of the combination sleeve. In general, the purpose of selecting block sizes is to maximize performance in order to adapt to the different characteristics of computing environment applications.
Array card Type
The first is the IDE array card, which used to be used primarily in servers and workstation computers that are important to data or to many hard drives, and can support RAID 0, 1, 0+1, 3, and 5. is now basically eliminated.
The second is SATA array card, mainly in large capacity data storage, Internet cafes, data security and other server areas, while some low-end cards also meet the needs of some home customers, can support RAID 0, 1, 0+1, 5, 6.
The third is that SCSI array cards are used on high-end workstations or servers and can support hard drives with many SCSI interfaces. Ability to support RAID 0, 1, 0+1, 3, 5. This array card performance is very good and fast of course the price is also relatively high. However, it is now largely obsolete.
The fourth is the SAS array card is mainly used in some high-end workstations and servers, has replaced the former SCSI interface, and can be compatible with SATA interface hard disk, can support RAID 0, 1, 0+1, 5, 50, 6, 60.
Disk array Benefits
Disk arrays have many advantages: first, improve the storage capacity, secondly, multiple disk drives can work in parallel, improve the data transmission rate, provide checksum redundancy, improve the security of the data ...
RAID technology does provide higher performance metrics, data integrity, and data availability than usual disk storage, especially when the current problem of I/O is always lagging behind the bottleneck of CPU performance, and the raid solution can effectively compensate for this gap.