Data protection can be achieved through the use of , in which part of the storage capacity is used to store redundant information about user data stored on the remainder of the storage capacity. The redundant information enables regeneration of user data if one of the disk physical disks in the fails.
RAID relies on a series of configurations, called levels, to determine how user and data is written and retrieved from the physical disks. This storage management software offers four formal RAID level configurations: RAID levels 5, 3, 1, and 0 described in the
following table, with each RAID level providing different types of data protection.
RAID Level
Data Protection Available
5
If a single physical disk fails in a RAID 5 disk group, all associated become , but the redundant information allows the data to be accessed.
If two or more physical disks fail in a RAID 5 disk group, all associated virtual disks fail, and all data is lost.
3
If a single physical disk fails in a RAID 3 disk group, all associated virtual disks become degraded, but the redundant information allows the data to be accessed.
If two or more physical disks fail in a RAID 3 disk group, all associated virtual disks fail, and all data is lost.
1
RAID 1/10 offers the best data availability, however, only half of the physical disks in the disk group are available for user data.
If a single physical disk fails in a RAID 1/10 disk group, all associated virtual disks become degraded, but the mirror physical disk allows the data to be accessed.
RAID 1/10 can survive multiple physical disk failures as long as no more than one failure exists per mirrored pair.
If a physical disk-pair fails in a RAID 1/10 disk group, all associated virtual disks fail, and all data is lost.
0
RAID 0 is not recommended for high availability needs. RAID 0 is better for non-critical data.
If a single physical disk fails in a RAID 0 disk group, all associated virtual disks fail, and all data is lost.