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RAID levels


  • Not recommended for database files
  • Does not provide fault tolerance
  • Provide disk striping
  • No redundancy
  • For testing purposes only


  • Recommended for transaction logs (optimal for sequential writes)
  • Provides fault tolerance and mirroring
  • High performance
  • Does not provide striping


  • Provides fault tolerance through parity and striping
  • No mirroring (uses fewer disks than RAID 1)
  • Not optimal for transaction logs that perform mostly sequential writes

RAID comparison

RAID level Mirroring Striping Parity
RAID 0 (not recommended) X
RAID 1 (for transaction logs) X
RAID 5 (read operations) X X
RAID 0+1 X X
  • RAID 1 and RAID 0+1 offers the best data protection and performance among RAID levels.
  • RAID 5 provides fault tolerance at the best cost but has half the write performance of RAID 1.
  • RAID 5 is not as fault tolerant as RAID 1 and RAID 0+1.
  • Mirroring requires two I/O write operations.
  • Parity requires four I/O write operations.
  • Read cost of mirroring and parity is the same.
notes/sql/raid.txt · Last modified: 2020/08/26 (external edit)