I was reading some ZFS pages on another discussion list I found this comment by few people who may or may not know something:
http://episteme.arstechnica.com/eve/forums/a/tpc/f/24609792/m/956007108831 [i]"You tend to get better write performance when the number of disks in the raid is (a power of 2) + 1, as the parity calculations are more efficient. ... 5 drives is better than 4 because you are more likely to write an entire stripe if it is the same size as your IO block, which is a power of 2. There is a thread around here somewhere that talks about that. RAID-Z always writes a full stripe, so that may not apply as much."[/i] It sounds like they're talking more about traditional hardware RAID but is this also true for ZFS? Right now I've got four 750GB drives that I'm planning to use in a raid-z 3+1 array. Will I get markedly better performance with 5 drives (2^2+1) or 6 drives 2*(2^1+1) because the parity calculations are more efficient across N^2 drives? This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
