In that case, this may be a much tougher nut to crack than I thought. I'll be the first to admit that other than having seen a few presentations I don't have a clue about the details of how ZFS works under the hood, however...
You mention that moving the old block means updating all it's ancestors. I had naively assumed moving a block would be relatively simple, and would also update all the ancestors. My understanding of ZFS (in short: an upside down tree) is that each block is referenced by it's parent. So regardless of how many snapshots you take, each block is only ever referenced by one other, and I'm guessing that the pointer and checksum are both stored there. If that's the case, to move a block it's just a case of: - read the data - write to the new location - update the pointer in the parent block Please let me know if I'm mis-understanding ZFS here. The major problem with this is that I don't know if there's any easy way to identify the parent block from the child, or an effcient way to do this move. However, thinking about it, there must be. ZFS intelligently moves data if it detects corruption, so there must already be tools in place to do exactly what we need here. In which case, this is still relatively simple and much of the code already exists. This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
