NetApp Backup Strategy - Snapshots to SnapMirrors to Tape?

Question

In a previous question we discussed the pros and cons of relying exclusively on NetApp snapshots for backups. I now find myself in this situation as our aging legacy Symantec BackupExec tape server catastrophically failed while rebuilding its RAID-1 array. Something, something, something proactive upgrading of critical systems . . .

Our current backup strategy is limited to on-filer Snapshots through either SnapManager for SQL, NetApp Virtual Storage Console vSphere Plugin (SMVI) or hopefully manually configured Volume Snapshots. These are then SnapMirror-ed offsite to another filer far, far away in the frozen wastes of the tundra where it is guarded by snow wookies.

Due to space constraints we age these Snapshots out rather quickly and previously relied on tape for retention periods longer than a month and as discussed in my other question there are number of other significant shortcomings with reliance on Snapshots and SnapMirrors as a sole source of backup and recovery.

We have a Dell TL4000 LTO-6 tape drive in our offsite location that is currently being used by an existing BackupExec 2010 R3 server. As a stop-gap, I want to use it to write our SnapMirror Volumes to tape.

I have some basic questions:

• Can I use NDMP to write our SnapMirror Volumes to tape? Everything I have read says this is very common and simple to setup. I really wish we had NetBackup not BackupExec but "you go to war with the army you have, not the one you wish you had"
• What happens if the SnapMirror changes during the NDMP job? Do I need to coordinate the SnapMirror sync times so they do not change during the backup process?
• How can I test my restores? With agent-based flat files, it's pretty dead simple but I'm not sure what the procedure would look like for a Volume-based backup.
• Any other general advice and/or noticeable problems with my plan?

Answer 1

I would advise seeing whether your backup software can initiate and manage SMTape backups from your secondary site. Even if it can't, you can use it through the Netapp CLI to back up the entire volume.

If your backup software supports it, you could use it to do full and incremental backups which would include all snapshots visible on the snapmirror destination, giving you a recoverable copy on another media that would have point in time granularity.

Can I use NDMP to write our SnapMirror Volumes to tape?

Yes, NDMP Dump does just this. It takes a single snapshot (either one that it creates itself, or one that you specify) and copies the filesystem to tape. Unlike SMTape, you save each snapshot as the whole filesystem it represents. SMTape saves each volume as a volume, including all the snapshots.

What happens if the SnapMirror changes during the NDMP job? Do I need to coordinate the SnapMirror sync times so they do not change during the backup process?

If a backup job using NDMP Dump is using a snapshot on the target and you delete that snapshot on the snapmirror source, one of two bad things might happen: Either the snapshot will get deleted on the target and the backup will fail, or the snapmirror update will fail until the snapshot is no longer busy on the destination. If you're doing the same thing with SMTape, I am also not sure which of the two it will fail. I know that it tries to back up any snapshots it sees at the start of the job, but I'm not sure what would happen if some snapshots were deleted while it was running.

How can I test my restores? With agent-based flat files, it's pretty dead simple but I'm not sure what the procedure would look like for a Volume-based backup.

NDMP Dump backups should be visible in the backup software you used to create them. If you created them without backup software, then you probably need to create a new R/W volume on the same filer you took them from and recover the whole volume to that in order to get a file.

SMTape backups should also be visible to the backup software, if it supports them, however if not, you will find instructions on how to do a recovery here.

Any other general advice and/or noticeable problems with my plan?

When this is all over, buy yourself a nice bottle of scotch.