>>> As others said, RAID6 is RAID5 + a hot spare. >> >> No. RAID6 is NOT RAID5 plus a hot spare. > > The original phrase was that RAID 6 was like RAID 5 with a hot spare > ALREADY BUILT IN.
Built-in, or not - it is neither. It is more than that, actually. RAID 6 is like RAID 5 in that it uses parity for redundancy and pays a write cost for maintaining those parity blocks, but will maintain data integrity in the face of 2 simultaneous drive failures. In terms of storage cost, it IS like paying for RAID5 + a hot spare, but the protection is better. A RAID 5 with a hot spare built in could not survive 2 simultaneous drive failures. -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
