aggr show_space interpretation

TERREMARK_BE — Thu, 05 Jun 2025 05:50:55 GMT

Hi all,

Currently I'm looking into a NetApp filer for which snapvault replication has issues because there is not enough space on the primary side to keep all changes in a snapshot.

I started looking at the output of aggr show_space -h and I wonder where some of the space goes.

I assume Usable space = total space(18TB) - WAFL Reserve (1913GB) - Snap Reserve (344GB).

Is A-SIS space that is taken out of the aggregate usable space?

Space allocated to volumes in the aggregate are Total Space allocated at the bottom of the output.

Used is the sum of the usage of all volumes. Usage of volumes is the sum of data and snapshots in that volume.

Please correct me if I got anything of this wrong.

This is what I can't decipher where space is going:

Aggregate Allocated Used Avail

Total space 15TB 10TB 560GB

4,5TB is gone for some reason: 15TB- 10TB = 560GB?

What am I missing here? Are there any other things that should be kept in account? Can someone give a drill down of all elements that are used to get to this number?

Are LUNs counted fully even half of the amount is used?

Is the target free space of a volume also taken into account?

As the volume usage seems correct, then we loose +4TB on the aggregate level? On what?

This is an example:

Aggregate 'aggr0_xxx_fc'

Total space WAFL reserve Snap reserve Usable space BSR NVLOG A-SIS Smtape

18TB 1913GB 344GB 16TB 0KB 919GB 0KB

Space allocated to volumes in the aggregate

Volume Allocated Used Guarantee

root_vol_delng153 162GB 8172MB volume

vol0 1350GB 1201GB volume

vol1 1348GB 940GB volume

vol2 1348GB 1012GB volume

vol3 1348GB 792GB volume

vol16 1348GB 1097GB volume

vol17 1347GB 864GB volume

vol18 1348GB 856GB volume

vol32 1372GB 802GB volume

vol45 2212GB 1663GB volume

vol46 2213GB 2002GB volume

Aggregate Allocated Used Avail

Total space 15TB 10TB 560GB

Snap reserve 344GB 217GB 127GB

WAFL reserve 1913GB 205GB 1708GB

Thanks in advance!

Re: aggr show_space interpretation

aborzenkov — Mon, 28 Oct 2013 11:30:11 GMT

For thick volumes (with reservation “volume”) full size is reserved in aggregate when volume is created and not available for anything else. “Used” shows actually used space and the rest is space reserved for volumes. If you sum all space allocated for volumes, you get ~ 15TB.

Re: aggr show_space interpretation

TERREMARK_BE — Tue, 29 Oct 2013 09:04:51 GMT

Thanks for that Aborzenkov!

Just one more thing that I wonder. IIRC you need to keep some space free for the SIS db on both the volume and the aggregate.

Is this space allocated in the WAFL reserve? I would think not.

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