Raid-array - solving problems with the speed of writing / reading and reliability of the system

A raid array is somewhat independent ofother drives that are interconnected through channels operating at a fairly high speed. The system perceives this combination as a single disk array. The management of the distribution of the processes of reading and writing occurs through the controller.

Raid array is used to maximizeIncrease write speed or reliability of disk storage. The solution of these issues can significantly improve the overall performance of the entire system.

Initially, creating a RAID array assumedcombining inexpensive discs. This undertaking was clearly reflected in the name itself (the abbreviation meant the following: “redundant array of inexpensive disks”). But later this technology, which proved to be high-quality and reliable, was transformed. A modern raid array is created, as a rule, on the basis of fairly expensive equipment. This, in turn, was again reflected in the name (today the abbreviation means “redundant array of independent disks”).

The development of the information society has strongly influenced the requirements that are put forward to the hardware, including the information repositories.

Therefore, since the raid array was created, several different sub-technologies have emerged that were developed to solve specific, narrowly focused tasks.

All the variety of tasks solved by computers requires equally diverse technological solutions. Types of raid arrays:

• RAID-0.In the simplest implementation, you must have two disks. The incoming information is recorded in blocks on both disks in turn. Reading involves the reverse process. This significantly speeds up the recording, but does not provide sufficient reliability, since an error on one of the disks leads to data loss in the entire array.
• RAID-1.In the simplest implementation, you must have two disks. Information received on the discs is recorded on them in full. This slows down the writing process, but, thanks to one hundred percent redundancy, provides a high level of reliability. The main advantage of this development is high fault tolerance and fast reading (as there is the possibility of reading from two disks at the same time).
• RAID-5. Failsafe array.In the simplest implementation, you must have three disks. Any recording of information occurs by breaking the data stream into blocks, each of which is assigned a checksum. In case of loss of data on one of the disks, they can be recovered using checksums recorded on others. Recovery requires the allocation of large capacities, so most often this implementation is used on server hardware.

The raid array of the fifth implementation is the mostcommon. This is due to its reliability and high speed of information processing, since one array can simultaneously conduct several independent processes of recording and reading information.