Pariteetketast

Pariteetketast, often translated as parity disk or parity drive, is a storage concept used in certain RAID (Redundant Array of Independent Disks) configurations. Its primary function is to provide data redundancy and enable data recovery in the event of a drive failure. Instead of storing actual data, a parity disk stores calculated parity information derived from the data on other disks within the array.

This parity information is not a direct copy of any single disk. Instead, it's a mathematical representation that allows for the reconstruction of the data from any single failed drive. When data is written to the array, parity is calculated and written to the designated parity disk. If one of the data disks fails, the system can use the data from the remaining disks and the parity information to rebuild the lost data onto a replacement drive.

Parity disks are a key component in RAID levels such as RAID 3, RAID 4, RAID 5, and RAID 6. The specific implementation and performance characteristics can vary depending on the RAID level. For instance, in RAID 5, parity is distributed across all disks, while in RAID 4, it's typically on a dedicated disk. The use of a parity disk significantly enhances the fault tolerance of a storage system, protecting against data loss without requiring a full mirror of all data.