On Sat, Apr 24, 2010 at 2:17 PM, Ragnar Sundblad <ra...@csc.kth.se> wrote:
> > On 24 apr 2010, at 16.43, Richard Elling wrote: > > On 24 apr 2010, at 09.18, Brandon High wrote: > > To answer the question you linked to: > > .shapshot/snapname.0/a/b/c/d.txt from the top of the filesystem > > a/.snapshot/snapname.0/b/c/d.txt > > a/e/.shapshot/snapname.0/c/d.txt > > a/e/c/.snapshot/snapname.0/d.txt > > I really don't understand what you mean, I think the path is there > just fine, and IMHO pretty much in the way you would expect. > > >> Make sense? > > > > Yes. The contents of the directory are there, but the full pathname does > > not follow because you changed a name in the path. Whether this is > > useful or not depends on whether you expect the path to be followed. > > > > It seems, the NetApp snapshot is a directory-level snapshot rather than a > > file system snapshot. I cannot see how to merge the two, so perhaps > > adding such a feature to ZFS could not leverage the file system snapshot? > > I believe NetApp snapshots are volume based in a fashion very much > like zfs volume snapshots. > >From the sounds of things, it would appear that NetApp snapshots happen at the volume/filesystem level. However, they also provide a "shortcut" .snapshot/ directory in every directory, allowing you to access that part of the tree directly. For example, with a filesystem root of /root: /root/branch/leaf/file.txt Snapshots are taken. You can either file.txt via any of the following: /root/.snapshot/branch/leaf/file.txt /root/branch/.snapshot/leaf/file.txt /root/branch/leaf/.snapshot/file.txt Wheras with ZFS you can only access file.txt via: /root/.zfs/snapshot/snapname/branch/leaf/file.txt >From the sounds of it, the .snapshot directory is just a pointer to the corresponding directory in the actual snapshot tree. The snapshots are not actually saved per-directory. They just give you a handy shortcut into that same level in the snapshot directory tree. Something like this would be very useful in ZFS, especially if you have deep directory trees in a single ZFS filesystem, and you want to compare files/directories in multiple snapshots. For example, our backups server has /storage/backup/.zfs/snapshot/snap-date/sitename/servername/home/u/username/yadda-yadda Which leads to very long cd commands to move between snapshots. Being able to just "cd .snapshot/snapname/" at arbitrary points in the tree, to access that part of the tree in another snapshot, would be handy. However, I've never actually used a NetApp system, so the above could be totally out in left field. It's just what I gathered from this discussion. -- Freddie Cash fjwc...@gmail.com
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