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RAID-5 Block Interleave Data Striping with Skewed Parity



RAID-5 Block Interleave Data Striping with Skewed Parity

The Raid-5 design tries to overcome all of these (RAID-0 to RAID-4) problems. Data is striped across the disks to ensure maximum read performance when accessing large files, while having the data striped in blocks improves the array's performance in a transaction processing environment. Parity information is stored on the array to guard against data loss, and skewing is used to remove the bottleneck that would be created by having all the parity information stored on a single drive.

 RAID-5 Block Interleave Data Striping with Skewed Parity
                     +----------+
                     |   Disk   |
                     |Controller|
                     +----+-----+
    +----------+----------+----------+-----------+
    |          |          |          |           |
 +--+---+   +--+---+   +--+---+   +--+---+   +---+--+
 |xxxxx |   |xxxxx |   |xxxxx |   |xxxxx |   |Parity|  Block 0
 |------|   |------|   |------|   |------|   |------|
 |xxxxx |   |xxxxx |   |xxxxx |   |Parity|   |xxxxx |
 |------|   |------|   |------|   |------|   |------|
 |yyyyy |   |yyyyy |   |Parity|   |yyyyy |   |yyyyy |
 |------|   |------|   |------|   |------|   |------|
 |      |   |      |   |      |   |      |   |      |  Block n
 +------+   +------+   +------+   +------+   +------+
  Disk 1     Disk 2     Disk 3     Disk 4     Disk 5
   xxxxx and yyyyy = Blocks belonging to long files

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