A RAID-5 volume is a fault-tolerant volume with data and parity striped intermittently across three or more physical disks. Parity is a calculated value that is used to reconstruct data after a failure. If a portion of a physical disk fails, the data on the failed portion can be recreated from the remaining data and parity. You can create RAID-5 volumes only on dynamic disks. You cannot mirror RAID-5 volumes.

The advantage of RAID-5 is that it provides fault tolerance with less hardware than that required for mirroring. RAID-5 supports the configuration of any number of data disks with the hardware cost of only one disk for parity. Mirroring requires separate disks for each mirror. RAID-5 protects against data loss when one disk fails. However, it is necessary to resynchronize the data from the other disks to access the data. With mirroring, if one disk fails, the data is available from another mirror right away. Also, RAID-5 does not have the advantage of adding more mirrors for increased fault tolerance. With mirroring, you can have three or more mirrors so that if more than one disk fails, there is still fault tolerance. With RAID-5, once two disks fail, the RAID-5 volumes on multiple disks fail. Now that the cost of storage has decreased, mirroring is a better choice for fault tolerance.

You can resynchronize a RAID-5 volume after it is degraded (having lost one disk).