aggregate snap reserve and automatic change in the value

[maskajan09]

Hello

what is causing the change in aggr snap reserve value? It drops from set value (15%) to 0% and the it returns. I would say if the storage needs more space in aggr it can reduce the snap reserve but I cannot find the process described in the documentation. Is it possible to control this behavior? Like lock it in the set value and do not allow any changes?

ONTAP 9.7

Thank you

[hmoubara]

Hello

The aggregate snapshot reserve should be a set value. Was there any operation done at the aggregate level that caused the percentage to change (resync per example, or system reboot..)? This happens because the original snapshot reserve is recorded only in memory. Reboot or takeover loses that information.

[maskajan09]

Thank you for your reply. 

I know that the aggr snap reserve can change up if you have SyncMirror and it needs more space for its snapshots. It is then reduced back to set value if the need for extra space is no more. So there must be some mechanism that can adjust the value. I was searching in netapp doc and google but had no luck finding any description of the mechanism.

They do not use SyncMirror. They only use SnapMirror. Just to clarify.

I don't think that it was just in memory. How could it be set only in memory? All changes are immediate and permanent. I don't know about some "save" command that must be run to preserve the configuration...Or do I miss something?

Thank you very much

[hmoubara]

Hello,

Can you share how much space is left on that aggregate that encounter that issue.

>storage aggregate show -aggregate <aggr name> -fields percent-used

> storage aggregate show-space -aggregate-name 

Thanks