Discrepancy between %Used and Used Capacity values

[ginolard2010]

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?

[peter_lehmann]

Do you have snapshots in the volume?

filer> snap list "volname"

Peter

[ginolard2010]

No, we don't use snapshots

[aborzenkov]

Show output of "df -h volname"

[ginolard2010]

Filesystem               total       used      avail capacity  Mounted on

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

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

[aborzenkov]

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?

[ginolard2010]

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? 

[aborzenkov · Accepted solution]

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.