Saturday, 30 November 2013

Setting Volume Attributes on SnapMirror Destinations

This post was inspired by OnCommand Unified Manager and an alert that came in about snapshot-reserve being over capacity on a SnapMirror destination volume. In my noobishness at NetApp storage administration, there I was scratching my head and thinking “do we have to break the SnapMirror and apply the attribute to the DR volume, then resync?” Completely wrong! (In fact, after breaking, attributes set on the DR volume would have been overwritten once we did the resync…)

As an example, I have a cluster called na81 with two Vservers - vs1 and vs2. There’s a volume called testshare on vs1 that’s being replicated to testDR on vs2.

na81::> snapmirror show
Source              Destination  Mirror        Relationship
Path          Type  Path         State         Status        Healthy
------------- ---- ------------ ------------- -------------- -------
na81://vs1/testshare DP na81://vs2/testDR Snapmirrored Idle  true

If I try to modify the % snapshot space (snapshot reserve) on the DR volume I get this error:

na81::> vol modify -vserver vs2 -volume testDR -percent-snapshot-space 20
Error: command failed: Unable to set volume attributes for volume "testDR" on Vserver "vs2". Reason: Unable to set attribute snapshot-reserve-percentage for volume. Reason: Operation not permitted on read-only volume 'testDR'

So, what we do to change the % snapshot space on the DR volume, is change it on the source and do a SnapMirror update. This is demonstrated below:

na81::> vol show -fields percent-snapshot-space
vserver volume percent-snapshot-space
------- ------ ----------------------
vs1     testshare 5%
vs2     testDR 5%

na81::> vol modify -vserver vs1 -volume testshare -percent-snapshot-space 20

na81::> vol show -fields percent-snapshot-space
vserver volume percent-snapshot-space
------- ------ ----------------------
vs1     testshare 20%
vs2     testDR 5%

na81::> snapmirror update -destination-path na81://vs2/testDR

na81::> vol show -fields percent-snapshot-space
vserver volume percent-snapshot-space
------- ------ ----------------------
vs1     testshare 20%
vs2     testDR 20%

Simples!

And it gives me an excuse to post an image of a cute meerkat!

Image: Cute meerkat...


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