topic Re: REDUCE lun size DATASTORE in ONTAP Discussions

REDUCE lun size DATASTORE

EBA — Thu, 05 Jun 2025 04:37:31 GMT

Hello,
I have a thick provisionned LUN in thin provisionied volume.

This LUN is attached to a ESX (datastore).
I want to reduce the LUN. Is there any risk of data loss?

It there is, how can I do this ?

Re: REDUCE lun size DATASTORE

aborzenkov — Thu, 09 Apr 2015 08:10:10 GMT

You can't reduce VMFS size: Reducing the size of a VMFS datastore

Re: REDUCE lun size DATASTORE

EBA — Thu, 09 Apr 2015 08:23:12 GMT

Thanks for your reply.

But I don't want to reduce the datastore.

I only want to reduce the lun which is used at 10% and is not growing.

I keep this KB for further use.

Re: REDUCE lun size DATASTORE

aborzenkov — Thu, 09 Apr 2015 08:34:43 GMT

You can't reduce LUN size without reducing size of filesystem on this LUN. 10% used space from host point of view does not mean only 10% is consumed on storage. Check actual space consumption with "lun show -v" - you cannot go below this value even if you disable space reservation for this LUN (without using deduplication and/or compression).

Storage vMotion as suggested in article I mentioned is really the most straightforward way to reduce space consumption.

Re: REDUCE lun size DATASTORE

EBA — Thu, 09 Apr 2015 08:45:52 GMT

Ok I understand.

Thanks a lot.

Re: REDUCE lun size DATASTORE

paulstringfellow — Thu, 09 Apr 2015 16:10:30 GMT

you can just thin provision the LUN, if you go to the LUN properties you can uncheck the fully provision option, this will thin provision the LUN and reduce it to it's actual size.