What are RAID levels, and how do they differ from one another?

What will be an ideal response?

The RAID level is determined by the method with which the hard disks are combined and by their number:

•  RAID 0. RAID 0 improves the performance of your data access; however, there is no redundancy in RAID 0. With RAID 0, two or more hard disks are pooled together (striping). Disk performance is very good, but the RAID system is vulnerable to a single point of failure. If one of the disks fails, all data is lost.

•  RAID 1. RAID 1 provides enhanced security for your data because the data is copied to one or several hard disks. This is also known as hard disk mirroring. If one disk is destroyed, a copy of its contents is available on the other disks. Minimum number of disks (or partitions) required for RAID 1 is two.

•  RAID 5. RAID 5 (Redundant Striping) is an optimized compromise between RAID 0 and RAID 1 in terms of performance and redundancy. Data and a checksum are distributed across the hard disks. Minimum number of disks (or partitions) required for RAID 5 is three. If one hard disk fails, it must be replaced as soon as possible to avoid the risk of losing all data on the array by failure of another disk. The data on the failed disk is reconstructed on its replacement from the data on the remaining disks and the checksum. If more than one hard disk fails at the same time, the data on the RAID 5 array is lost.

•  RAID 6. RAID 6 is comparable to RAID 5, with the difference being that two disks may fail without data loss. The minimum number of disks (or partitions) required for RAID 6 is four.