On Wed, Sep 12, 2007 at 07:39:56PM -0500, Al Hopper wrote: > >This is how RAIDZ fills the disks (follow the numbers): > > > > Disk0 Disk1 Disk2 Disk3 > > > > D0 D1 D2 P3 > > D4 D5 D6 P7 > > D8 D9 D10 P11 > > D12 D13 D14 P15 > > D16 D17 D18 P19 > > D20 D21 D22 P23 > > > >D is data, P is parity. > > > >And RAID5 does this: > > > > Disk0 Disk1 Disk2 Disk3 > > > > D0 D3 D6 P0,3,6 > > D1 D4 D7 P1,4,7 > > D2 D5 D8 P2,5,8 > > D9 D12 D15 P9,12,15 > > D10 D13 D16 P10,13,16 > > D11 D14 D17 P11,14,17 > > Surely the above is not accurate? You've showing the parity data only > being written to disk3. In RAID5 the parity is distributed across all > disks in the RAID5 set. What is illustrated above is RAID3.
It's actually RAID4 (RAID3 would look the same as RAIDZ, but there are
differences in practice), but my point wasn't how the parity is
distributed:) Ok, RAID5 once again:
Disk0 Disk1 Disk2 Disk3
D0 D3 D6 P0,3,6
D1 D4 D7 P1,4,7
D2 D5 D8 P2,5,8
D9 D12 P9,12,15 D15
D10 D13 P10,13,16 D16
D11 D14 P11,14,17 D17
--
Pawel Jakub Dawidek http://www.wheel.pl
[EMAIL PROTECTED] http://www.FreeBSD.org
FreeBSD committer Am I Evil? Yes, I Am!
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