2009-01-14 10:48 AM
Can someone briefly explain what functionality SnapRestore adds above manually copying files out of the .snapshot directory on a volume? NB. I am thinking about NFS/CIFS volumes here.
Forgive this basic question, but it will still be a while before I get access to a Filer for evaluation and I'm trying to understand the different NetApp software options.
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2009-01-14 10:53 AM
If all you want to do is occasionally restore a few small files, then that's just fine. However, SnapRestore allows you to revert an entire volume regardless of size back to a given snapshot in a very short period of time. So even a 16TB volume can be reverted in a couple of seconds. In addition, you can restore single files quickly. This is really useful on very large files (like LUNs which can be several TBs). Copying that through a NAS host could take hours (or maybe days). SnapRestore allows that to happen very quickly.
Hope this helps.
2009-01-14 11:04 AM
Ah, so am I right in thinking that without SnapRestore there isn't a command to rollback a whole volume to a prior snapshot?
I am familiar with ZFS*, are you saying that SnapRestore allows me to do something analogous to:
zfs rollback volume@snapshot
I assume SnapRestore can be used from GUI and command line? What would an example CLI command for a SnapRestore of a whole volume be?
You mention that SnapRestore allows you to quickly restore individual files. Can you expand on this a bit? Do you mean if I copy the file from the .snapshot directory I'm effectively copying all the blocks, whereas with SnapRestore it just reverts the changed blocks for that file?
*I do realise that Sun and NetApp are not on the best of terms, but it's the best analogy I could come up with my experience. Please don't flame me
2009-01-14 05:42 PM
Adam is referencing that Snap Restore will use a Snapshot that was taken at a particular point in time (that contains some blocks that are no longer part of the active file system due to changes) and will reassociate the Active File System's pointers back to those blocks (and away from the changes that have taken place since)--making this the newly restored active file system. This is true whether it is a file or a volume.
The difference between using Snap Restore and using a host OS to copy files out of the Snapshot directory is that the copy approach (the latter) has to utilize the network and the *host* processor/memory to affect the move--this would not be practical for large amounts of data. Snap Restore allows this process to take place on the NetApp controller without involving an external host (and, as Adam stated, is therefore very fast).
For vol: snap restore -t vol -s <snapshot name> <vol name> there are other flags
For file: snap restore -t file /vol/volname/filename there are other flags for alternate location, etc.
I hope this helps.