On 10/25/06, Jonathan Edwards <[EMAIL PROTECTED]> wrote:
On Oct 24, 2006, at 12:26, Dale Ghent wrote: > On Oct 24, 2006, at 12:33 PM, Frank Cusack wrote: > >> On October 24, 2006 9:19:07 AM -0700 "Anton B. Rang" >> <[EMAIL PROTECTED]> wrote: >>>> Our thinking is that if you want more redundancy than RAID-Z, >>>> you should >>>> use RAID-Z with double parity, which provides more reliability >>>> and more >>>> usable storage than a mirror of RAID-Zs would. >>> >>> This is only true if the drives have either independent or identical >>> failure modes, I think. Consider two boxes, each containing ten >>> drives. >>> Creating RAID-Z within each box protects against single-drive >>> failures. >>> Mirroring the boxes together protects against single-box failures. >> >> But mirroring also protects against single-drive failures. > > Right, but mirrored raidz would in this case protect the admin from: > > 1) one entire jbod chassis/comm failure, and > 2) individual drive failure in the remaining chassis during an > occurrence of (1) > > Since the person is dealing with JBODS and not hardware RAID > arrays, my suggestion is to combine ZFS and SVM. > > 1) Use ZFS and make a raidz-based ZVOL of disks on each of the two > JBODs > 2) Use SVM to mirror the two ZVOLs. Newfs that with UFS. > > Not at all optimal, but it'll work. It would be nice if you could > manage a mirror of existing vdevs within ZFS and this mirroring > would be a special case where it would be dumb and just present the > volume and pass through most of the stuff to the raidz (or > whatever) vdev below. It would be silly to double-cksum and > compress everything, not to mention the possibility of differing > record sizes. RFE submitted as 6485689
I'm willing to work on this if no one else is. :) -- Regards, Jeremy _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
