> From: Richard Elling [mailto:richard.ell...@gmail.com] > > One last try. If you change the "real" directory structure, how are > those > changes reflected in the "snapshot" directory structure? > > Consider: > echo "whee" > /a/b/c/d.txt > [snapshot] > mv /a/b /a/B > > What does /a/B/c/.snapshot point to? If the answer is "nothing," then > I see > significantly less value in the feature.
Actually, I find this very surprising: Question posted: http://lopsa.org/pipermail/tech/2010-April/004356.html Answered: http://lopsa.org/pipermail/tech/2010-April/004358.html My comments about it: http://lopsa.org/pipermail/tech/2010-April/004361.html and http://lopsa.org/pipermail/tech/2010-April/004362.html So apparently, the netapp snapshot is more directory based, and not so much filesystem based. Very surprising, to me. But this is good, because if implemented in ZFS, it leaves room for improvement: There's no reason why the snapshots under "a" couldn't be identical to the snapshots under "a/e" The only difficulty is for the filesystem to recognize a "mv" command as such, and to link things appropriately behind the scenes. In this case, "mv" is different from "cp ; rm" which was a long-time problem of svn, analogous to this one in the filesystem. But eventually, svn got it right, and now recognizes "mv" should preserve the history for items after they're renamed. IMHO, the (ideal) desired behavior is *neither* what ZFS currently does, or what netapp currently does. IMHO, the ideal desired behavior is as described in that last email above. Namely: * Let the snap of the parent directory remain the same as it was at the time of the snapshot, And * Let the snapshots of the renamed subdirectory go along with the new name of the subdirectory. Anyway, it's all pointless at this moment. Because obviously that's all nontrivial, and very diminishing returns. So I maintain very near zero hope that it'll ever happen. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
