On Mon, Aug 13, 2012 at 10:40:45AM -0700, Richard Elling wrote: > > On Aug 13, 2012, at 2:24 AM, Sa?o Kiselkov wrote: > > > On 08/13/2012 10:45 AM, Scott wrote: > >> Hi Saso, > >> > >> thanks for your reply. > >> > >> If all disks are the same, is the root pointer the same? > > > > No. > > > >> Also, is there a "signature" or something unique to the root block that I > >> can > >> search for on the disk? I'm going through the On-disk specification at the > >> moment. > > > > Nope. The checksums are part of the blockpointer, and the root > > blockpointer is in the uberblock, which itself resides in the label. By > > overwriting the label you've essentially erased all hope of practically > > finding the root of the filesystem tree - not even checksumming all > > possible block combinations (of which there are quite a few) will help > > you here, because you have no checksums to compare them against. > > > > I'd love to be wrong, and I might be (I don't have as intimate a > > knowledge of ZFS' on-disk structure as I'd like), but from where I'm > > standing, your raidz vdev is essentially lost. > > The labels are not identical, because each contains the guid for the device. > It is possible, though nontrivial, to recreate. > > That said, I've never seen a failure that just takes out only the ZFS labels.
You'd have to go out of your way to take out the labels. Which is just what I did (imagine: moving drives over to USB external enclosures, then putting them onto a HP Raid controller (which overwrites the end of the disk) - which also assumed that two disks should be automatically mirrored (if you miss the 5 second prompt where you can tell it not to). Then try and recover the labels without really knowing what you're doing (my bad). Suffice to say I have no confidence in the labels of two drives. On OI I can forcefully import the pool but with any file that lives on multiple disks (ie, over a certain size), all I get is an I/O error. Some of datasets also fail to mount. Thanks everyone for your input. > -- richard > > -- > ZFS Performance and Training > richard.ell...@richardelling.com > +1-760-896-4422 > > > > > > > _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
