10 Aug
1999
10 Aug
'99
8:18 p.m.
I think RAID4/RAID5 is cannot be as performant as RAID1 (Mirror), because the parity bits need to be recalculated for every bit written.
Addition is cheap, so that is not an issue. What may be an issue is retrieving parity data from the array, but that can easily be cached. There are two writes in RAID 4/5 just as there are in RAID 1.
Actually, if you write N data blocks that correspond to the same parity block, you only do N+1 writes for the N blocks.
Steve Losen scl@virginia.edu phone: 804-924-0640
University of Virginia ITC Unix Support