Keep retention and auto-delete on snapshots when removing schedule

[Göran]

We will move a volume, with snapmirror all snapshots, that contains snapshots with long retention. No new snapshot will be taken on the destination when mirroring is complete.

Is there a way to set up a snapshot policy that maintain the retention of the snapshots, i.e. delete the daily snapshots when retention period is outdated? 

RETENTION COUNT 

daily 60 weekly 52 monthly 36

[Tas]

Göran, should I assume that you are snapmirroring to a secondary array?  If so, then you need to setup up a "MirrorAndVault" policy on your secondary that mirrors the latest active file system and daily and weekly snapshots from the source.  You can them specify a retention for you daily or weeklies on the secondary.

Depending on your re-write rate, (daily snapshot size), you may not need to keep that many snapshots; you could just keep 1080 dailies or say 36 monthlies.  If on the primary you have 60 dailies, I presume your re-write rate is low;  are you keeping 52 weeklies and 36 monthlies as well? Is your volume not out of space?

Or is that what you would like to keep on the secondary?

[Göran]

Thanks Tas

I just want to keep the snapshots in the mirrored volume, mirrored with MirrorAllSnapshots policy.

No new snapshot shall be taken on the volume. 

So the question is: Is it possible to get the the snapshots deleted when the retention is out?
What I came up to is that is not possible to get Ontap to do as the retention is a number of snapshot i.e. daily 60 and the oldest will be deleted when the 61:st is created. And as I said no more snapshots shall be taken as these backup just shall be kept until retention is reached.

[Tas · Accepted solution]

I think I see.  You want to retain your volume with all snapshots as of, say today, on your array (primary or secondary).  All you need do is change your snapshot policy to none.  By doing so, no new snapshots will be created, and none rotated/deleted.  You will have to do it manually at the end of your rotation period. 
Is that what you were asking?  You can check it by setting your policy to none, and checking your next daily.  It should still be there.

If you need to lock the volume for legal reasons, you can also do that, but you need to speak to your sales rep to see if you have the license.

Don't forget to quiesce and break your snapmirror if your volume is secondary so it doesn't update the base.

[Göran]

Yes, that's right.

That's what I asumed, that we have to keep track of the retention and delete manually.

Thanks Tas