topic Re: volume size display error after deduplication in ONTAP Discussions

volume size display error after deduplication

vantagemedia — Thu, 05 Jun 2025 06:23:04 GMT

I have an interesting problem, I performed a deduplication on a volume that contained a space reserved LUN.

After doing much reading, this is effectively a configuration that while works, provides none of the benefits.

Further reading has people saying to turn off LUN space reservation when you have space guarantees set to volume at the FlexVol level.

This is all fine, however now that I have done that, the space the volume is reporting is inaccurate.

I have a volume that is 1TB in size and it is showing that it is almost completely free, even though I have a LUN on it, and at the host level that LUN contains considerable data&colon;

na2*> df -h vmware_02

Filesystem total used avail capacity Mounted on

/vol/vmware_02/ 999GB 53MB 999GB 0% /vol/vmware_02/

/vol/vmware_02/.snapshot 249GB 2512KB 249GB 0% /vol/vmware_02/.snapshot

na2*> df -sh vmware_02

Filesystem used saved %saved

/vol/vmware_02/ 53MB 174MB 76%

na2*> lun show /vol/vmware_02/v2

/vol/vmware_02/v2 1.0t (1099529453568) (r/w, online, mapped)

As you can see at the VMware level, that LUN is 1TB that has 600gb used, yet clearly at the NetApp level it sees the volume as empty.

My first thoughts are that this is a bug, and that running deduplication on a volume that contained a space reserved LUN has tickled a bug.

Anyone have any insight here?

Re: volume size display error after deduplication

aborzenkov — Tue, 10 Jul 2012 16:55:34 GMT

Please show output of “df -S” instead (or small “s”, I do not remember which version supports which flag).

volume size display error after deduplication

vantagemedia — Tue, 10 Jul 2012 19:20:53 GMT

na2> df -S vmware_02

Filesystem used compressed a-sis %saved

/vol/vmware_02/ 55192 0 178584 76%

Filesystem used saved %saved

/vol/vmware_02/ 53MB 174MB 76%

Re: volume size display error after deduplication

aborzenkov — Wed, 11 Jul 2012 08:30:48 GMT

It would be interesting to see “lun show -v” to see actual space consumption (which version of Data ONTAP BTW?) and “aggr show_space”.

Are you absolutely sure it is really the same LUN and volume?

Re: volume size display error after deduplication

vantagemedia — Wed, 11 Jul 2012 15:06:16 GMT

na2*> lun show -v /vol/vmware_02/v2

/vol/vmware_02/v2 1.0t (1099529453568) (r/w, online, mapped)

Serial#: Hn/3NZl6kAst

Share: none

Space Reservation: disabled

Multiprotocol Type: vmware

Maps: igroup_vmware_fc=8

Aggregate 'aggr6_sata'

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

9546637056KB 954663680KB 85919732KB 8506053644KB 0KB 534644KB

Space allocated to volumes in the aggregate

Volume Allocated Used Guarantee

backups 210880284KB 53531752KB volume

vmware_nosnap_02 1187256000KB 55901480KB volume

vmware_02 1316947376KB 83956KB volume

Aggregate Allocated Used Avail

Total space 2715083660KB 109517188KB 5790117788KB

Snap reserve 85919732KB 17870608KB 68049124KB

WAFL reserve 954663680KB 7930032KB 946733648KB

na2*> version

NetApp Release 7.3.3: Thu Mar 11 22:29:52 PST 2010

Re: volume size display error after deduplication

aborzenkov — Wed, 11 Jul 2012 15:26:04 GMT

Well … it looks like it the correct LUN (at least, serial number matches). Unfortunately, Data ONTAP is too old and does not show “Occupied size”.

Does VMware have something like “thin provisioning” too? Is it possible that it has 600GB reserved, but not actually used? IIRC it has different VMDK modes; one of them is “allocate but zero out on first access”, which sounds like it may be the case.

Have you tried to ask on VMware communities?