My understanding of aggregate snapshots is that they provide an additional layer of snapshot protection, and are useful in some environments.
restoring an aggregate snapshot restores *all* the flexVols within that aggregate. aggregate snapshots are required if you use RAID SyncMirror and/or MetroCluster configurations. or of you want to snaprestore a whole aggregate (seems dangerous).
Note that aggregate snapshots aren't allowed to grow abouve the reserve, and will "autodelete" themselves to maintain space.
on my test filers and in my test use of the simulator, I've been running with aggregate snapshots disabled and the reserve set to 0. NetApp "discourages" this, but unless they send me 5% more disks, free, I want that space back for production.
-skottie
Steve Losen wrote:
We just got a R200 and FAS960c and I immediately upgraded them from 6.5 to 7.0.0.1. I moved the root volume to a flex vol and destroyed the old root, so now I have one big aggregate that contains the root volume.
I discovered the "df -A" command and was surprised to see that my aggregate has snap reserve space, a snap sched running, and five snapshots. This is independent of the snap reserve and sched of my root volume.
What is the rationale behind aggregate snapshots? We don't have snapmirror licensed. Can you snapmirror them? Can you snaprestore them? I presume this mirrors (or restores) the entire aggregate. I doubt that you can access aggregate snapshots from a NFS or CIFs client, or can you? Can you somehow tease out volumes from an aggregate snapshot and NFS export them? Within an aggregate snapshot, do you have just the active volumes, or the volumes and all of their volume level snapshots as they existed at the time the aggregate snapshot was taken? Mind boggling.
I am probably going to set the snap reserve on my aggregates to zero and turn off the snap sched and manage my snapshots at the volume level. Any reason to not do that? Using both aggregate and volume snapshots looks about the same as using a belt and suspenders to keep your pants up.
Steve Losen scl@virginia.edu phone: 434-924-0640
University of Virginia ITC Unix Support