On Thu, Sep 17, 2009 at 01:32:43PM +0200, Eugen Leitl wrote: > > reasons), you will lose 2 disks worth of storage to parity leaving 12 > > disks worth of data. With raid10 you will lose half, 7 disks to > > parity/redundancy. With two raidz2 sets, you will get (5+2)+(5+2), that > > is 5+5 disks worth of storage and 2+2 disks worth of redundancy. The > > actual redudancy/parity is spread over all disks, not like raid3 which > > has a dedicated parity disk. > > So raidz3 has a dedicated parity disk? I couldn't see that from > skimming http://blogs.sun.com/ahl/entry/triple_parity_raid_z
Note that Tomas was talking about RAID-3 not raidz3. To summarize the RAID levels: RAID-0 striping RAID-1 mirror RAID-2 ECC (basically not used) RAID-3 bit-interleaved parity (basically not used) RAID-4 block-interleaved parity RAID-5 block-interleaved distributed parity RAID-6 block-interleaved double distributed parity raidz1 is most like RAID-5; raidz2 is most like RAID-6. There's no RAID level that covers more than two parity disks, but raidz3 is most like RAID-6, but with triple distributed parity. Adam -- Adam Leventhal, Fishworks http://blogs.sun.com/ahl _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
