Solved: Recommended aggregate free space for AFF models

AlexeyF · ‎2022-09-12

Hi

I would like to know the guidelines for the aggregates capacity usage levels for AFF A250 model.

As I've heard for FAS models it was recommended to keep around 20% of free space in the aggregate. Otherwise ait resulted in a performance degradation.

What about AFF disk arrays, can we fill it up to 90% - 95% - 99% from a performance point of view?

Thanks,

Alexey

paul_stejskal · ‎2022-09-12

Yes you can push it. The biggest reason was because of finding full stripes in RAID to write is much harder with a full file system. But SSDs are so fast that you run out of CPU before you do disk, so generally this isn't a problem. Also with AFF you can use FabricPool to offset some of that space. Some customers use that for snapshots, but you need to plan that out very well because there is definitely a performance penalty for using FabricPool.

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paul_stejskal · ‎2022-09-12

Yes you can push it. The biggest reason was because of finding full stripes in RAID to write is much harder with a full file system. But SSDs are so fast that you run out of CPU before you do disk, so generally this isn't a problem. Also with AFF you can use FabricPool to offset some of that space. Some customers use that for snapshots, but you need to plan that out very well because there is definitely a performance penalty for using FabricPool.

SpindleNinja · ‎2022-09-12

The number that I've heard throughout my working with ONTaP is that 95% is the % of max for aggrs before a potential perf impact.