ONTAP Hardware

Maximum space used for an Aggregate


Hi all, I have a question about how much space of an Aggregate can be used, what the best practice is.

We currently have a SAN with 4 Aggregates.

  1. Aggr0 is the system aggregate, 96% is used of this aggregate.
  2. Aggr1 is devided between cifs and vols, 99% of this aggregate is being used.
  3. Aggr2 is devided between cifs and vols and 95% of this aggregate is being used.
  4. Aggr3 still has 6TB of space left and will be fully utilized in the near future.

My question is, is there a maximum usage of space for an aggregate? For the last couple of days I'm getting the message 'Critical: Aggregate aggr1_01 on node "name" is 99% used' and 'Critical: Aggregate aggr2_02 on node "name" is 95% used'. Nothing has happened yet, no deteriozation of speed or anything like that. I think the alarm threshold has been put in by the company who helped us setting up the SAN. But I was wondering what the best practice is for an Aggregate space usages.

Hope to hear from you soon and thank you for your time.




We strive for high utilization and get nervous at 95% or above.  If you are thin provisioning, like we do then I really try not to go above 95%.  With that said we only see performance issues when its 99% or more full.  You may have aggregate snapshots on and you can usually get 5% back.

FAS3070*> snap sched -A

Aggregate aggr64: 0 0 0

FAS3070*> snap reserve -A

Aggregate aggr64: current snapshot reserve is 0% or 0 k-bytes.

If you have aggregate snapreserve, was 5% default for quite some time, you can change that to 0 and then set the aggregate snap shot schedule to 0 0 0.  You don't need aggregate snapshots, they are only used for Metrocluster.


above 90% usage you will have performance degradation.

now it depends if you have enabled thin provisioning or not. if you don't use thin provisioning, it may show a 99% full aggregate with df -A,

but you may still have space left.

if you use thin provisioning, then don't go over 90%!

have a look at aggr show_space (-h), there you can see the usable space.

and keep an eye on the snapshots. maybe there are old snapshots to delete on the volumes.