topic Discrepancy between %Used and Used Capacity values in ONTAP Discussions

Discrepancy between %Used and Used Capacity values

ginolard2010 — Thu, 05 Jun 2025 06:48:31 GMT

Maybe I am missing something obvious but I don't understand this situation

We have a FlexVol of 3TB, Space Guarantee = None

The volume contains a single 1.5TB LUN, Space Reservation = None

The filesystem on the Lun (Linux) reports 81% used

However, when I check the stats of the volume the %Used is 80% but the Used Capacity is 1.41 TB

Why is the %Used value so high?

Discrepancy between %Used and Used Capacity values

peter_lehmann — Tue, 09 Aug 2011 07:50:36 GMT

Do you have snapshots in the volume?

filer> snap list "volname"

Peter

Discrepancy between %Used and Used Capacity values

ginolard2010 — Tue, 09 Aug 2011 08:43:50 GMT

No, we don't use snapshots

Re: Discrepancy between %Used and Used Capacity values

aborzenkov — Tue, 09 Aug 2011 16:06:01 GMT

Show output of "df -h volname"

Discrepancy between %Used and Used Capacity values

ginolard2010 — Wed, 10 Aug 2011 05:48:20 GMT

Filesystem total used avail capacity Mounted on

/vol/volrh2/ 3072GB 1448GB 610GB 80% /vol/volrh2/

/vol/volrh2/.snapshot 0GB 0GB 0GB ---% /vol/volrh2/.snapshot

Re: Discrepancy between %Used and Used Capacity values

aborzenkov — Wed, 10 Aug 2011 05:53:38 GMT

OK, so two possibilities

- Some space is reserved for snapshots (look at “df -r”)

- If volume is thin provisioned, “available” reflects free space in contained aggregate. What “df -Ah aggr-for-volrh2” says?

Re: Discrepancy between %Used and Used Capacity values

ginolard2010 — Wed, 10 Aug 2011 06:05:00 GMT

Doesn't look like space is reserved for snapshots. As I said, we don't use them at all

Filesystem kbytes used avail reserved Mounted on

/vol/volrh2/ 3221225472 1519112992 640049348 0 /vol/volrh2/

/vol/volrh2/.snapshot 0 0 0 0 /vol/volrh2/.snapshot

output of df -Ah is

Aggregate total used avail capacity

aggr1 8724GB 8114GB 610GB 93%

aggr1/.snapshot 459GB 226GB 232GB 49%

This is the output for Get-Navol for that aggregate

volrh1 online 819,2 GB 61% 317,8 GB False 109 32M aggr1

volrh2 online 3,0 TB 80% 610,3 GB False 109 32M aggr1

volwin1 online 1,4 TB 35% 923,4 GB False 109 32M aggr1

volwin2 online 4,5 TB 87% 590,1 GB False 116 32M aggr1

volrh2 and volwin2 are thin provisioned, the other two have a space guarantee of "volume".

volwin2 contains two 2TB "Space Reserved" luns so I guess that 590GB of free space is never going to be used by the volume.

Should I be worried now?

Re: Discrepancy between %Used and Used Capacity values

aborzenkov — Wed, 10 Aug 2011 06:23:05 GMT

This explains why used + avail do not match total. As for why %used and Used do not match … well, I guess (total – avail)/total simply provides better approximation. Avail can be less than (total – used) under many conditions.

But to get definite answer you need to look at the sources after all ☺ In general I guess “avail” is the only thing that finally matters.