Accepted Solution

Volume usable size and lun


I have trying to understand the space usage a volume displays when a lun is created in it. For example,

volume size =625g (guarantee=none)

lun size=500g (space reservatio=disabled)


There is a snapshot(snapmirror) in te volume

The lun show -v command reports the lun consumtion as 363g

The df -g output of the volume reports 27gb usaed and 597gb free. whereas the host sees 90% utilised for the same lun mounted as a datastore? I am having a hard time understanding this equation. If the volume usage reported more than the what is reported in the host side than I would have understood that that there was sme changes in the data and space reclamation needed to be run. But I am not able to understand why would a volume report only 27g of usage and 597g of availble space.

Any suggestions would be greatly appreciated.



Re: Volume usable size and lun

please, show ouput of

lun show -v

df -h

df -rh

aggr show_space

Re: Volume usable size and lun

I would suggest its because you have a thin provision LUN.

How much data is actually on the LUN as far as the OS is concerned?

Re: Volume usable size and lun

Interesting. Are you using deduplication on this volume?

Re: Volume usable size and lun

I always was under impression, that “Occupied size” is exactly the actual amount of data on LUN. I may be wrong; do you know what this field means?

Re: Volume usable size and lun

I’d agree, that that is what you’d expect…however I think it means how much data has been written to the LUN…

I think the useful starting point would be to find out how much data the OS actually sees as been on the LUN and from there we can probably work out what’s happening…

It an odd world really because of the disconnect between what the OS thinks is on a disk and what is actually in the LUN…seen it this week..where LUNS are filled…however the OS says its only using 60% of the disk…but its caused by data been deleted…hence space reclamation…

Not sure the ontap commands are an exact science for stuff like this…be interested to see the actual disk usage shown by the OS and work from there…

Re: Volume usable size and lun

More likely it is due to “A-SIS = 97377440KB”, which is “Amount of disk space used by deduplication metadata in the aggregate”. I bet on active deduplication ☺ Rahul, could you additionally show output of “df -s” (I always forget this option, sorry).

Re: Volume usable size and lun

Thanks Aborzenkov, below is the output of df -s

Filesystem                used      saved       %saved

/vol/volxxx/          29105600  351716240          82%


From the host side, the used capacity is shown as

500G  440G   59G  92% /vmfs/volumes/NetApp-DP-T-120-xxx

If the volume usage showed more than what the host is reporting, than I would have understood that space reclaimer needs to be run as there might have been lot of data changes from the host side. Since the usage on the host side shows more than what the storage is reporting, I got confused.



Re: Volume usable size and lun

So you have here 360+G your LUN occupies. We found it ☺

Re: Volume usable size and lun

Think the dedupe stat tells you everything there…getting 92% dedupe…hence the space saving…

Gotta love that NetApp technology!!!