RAID - Redundant Array of Independent Disks

​Term RAID stands for Redundant Array of Independent Disks. RAID means that more than one drive will be used. I will try to explain common RAID levels.

Common RAID levels are 0, 1, 5. More advanced RAID levels are 10 and 50.

RAID level 0 is striping, when data is written or read from two drives. RAID 0 does not provide any redundancy. It is used to increase write and read performance. If one of drivers in RAID 0 fails then data in second drive will be unavailable as well.

RAID 1 is called mirroring. The data which is written in one drive is duplicated to another one. RAID 1 does not provide any performance improvements for write operations, however it can improve read operations.

RAID 5 is good for redundancy. Drives are configured this way that data which is written there is written to all drives. Data is split, so only a portion of data is written to each drive. RAID level 5 requires at minimum three drivers to operate. Two drives will be used for data and one for parity.

RAID 10 is mirroring with striping, and RAID 50 adds striping to RAID 5 disk array.

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