Urgh. This is going to be harder than I thought -- not impossible, just hard.
When we detach a disk from a mirror, we write a new label to indicate that the disk is no longer in use. As a side effect, this zeroes out all the old uberblocks. That's the bad news -- you have no uberblocks. The good news is that the uberblock only contains one field that's hard to reconstruct: ub_rootbp, which points to the root of the block tree. The root block *itself* is still there -- we just have to find it. The root block has a known format: it's a compressed objset_phys_t, almost certainly one sector in size (could be two, but very unlikely because the root objset_phys_t is highly compressible). It should be possible to write a program that scans the disk, reading each sector and attempting to decompress it. If it decompresses into exactly 1K (size of an uncompressed objset_phys_t), then we can look at all the fields to see if they look plausible. Among all candidates we find, the one whose embedded meta-dnode has the highest birth time in its dn_blkptr is the one we want. I need to get some sleep now, but I'll code this up in a couple of days and we can take it from there. If this is time-sensitive, let me know and I'll see if I can find someone else to drive it. [ I've got a bunch of commitments tomorrow, plus I'm supposed to be on vacation... typical... ;-) ] Jeff On Tue, Apr 29, 2008 at 12:15:21AM -0700, Benjamin Brumaire wrote: > Jeff thank you very much for taking time to look at this. > > My entire pool consisted of a single mirror of two slices on different disks > A and B. I attach a third slice on disk C and wait for resilver and then > detach it. Now disks A and B burned and I have only disk C at hand. > > bbr > > > This message posted from opensolaris.org > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
