On Aug 13, 2012, at 8:59 PM, Scott wrote: > 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).
ouch. But that shouldn't be enough. > Then try and recover the labels without really knowing what you're doing (my > bad). d'oh! > 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. please tell me you imported readonly? -- richard > > Thanks everyone for your input. > >> -- richard >> >> -- >> ZFS Performance and Training >> richard.ell...@richardelling.com >> +1-760-896-4422 >> >> >> >> >> >> >> -- ZFS Performance and Training richard.ell...@richardelling.com +1-760-896-4422
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