ONTAP Discussions

downsizing a volume

Hi Fellow NetApp users and experts 


We are using Data ONTAP 8.2.3p3 7-mode and all of our flexvols are presented as FC LUN datastores to our VMware environment.


We have a 1TB flexvol which is snapmirrored to a remote filer currently holding a few Virtual servers for our VMware cluster.


Over recent months we have decommisioned a lot of servers which were previously held on this volume and now the volume provisioned space is only taking up 80GB so my thinking is to recreate another smaller flexvol e.g. 100GB, using VMware Storage VMotion to move the remaining VMs to this new volume and then destory the 1TB volume however I want to preserve the current snapmirror relationships and move these over to the new volume so no baseline needs to be performed.


On the NetApp side the volume is showing still as 500GB consumed, it is a thin provisioned volume.


As we are using v5.0 of vsphere I know we could use disk reclaim tools to reclaim the storage back on the NetApp side but due to the size of the remaining VMs on the volume (about 75GB) I think it would be easier to recreate a new volume and its a real headache in the version of ESXi we are using.


I have two questions:


  • Can I reduce the size of the flexvol and LUN dynamically using OnCommand Manager? Can I do this while the VMs are running? If this cannot be done
  • Is there a process I can run on the filer to move the snapshots from old volume to new volume?


Many thanks



Re: downsizing a volume

  • Can I reduce the size of the flexvol and LUN dynamically using OnCommand Manager?



  • Can I do this while the VMs are running?

Yes for FlexVol, no for LUN. It has nothing to do with NetApp - you cannot reduce size of VMFS.


  • Is there a process I can run on the filer to move the snapshots from old volume to new volume?

SnapMirror, vol copy, but I do not see how it helps you. You will get exactly the same LUNs that you want to get rid of.

Re: downsizing a volume

Thank you for that quick reply.


ok based on your reponse. In your opinion am I best just creating a new volume and creating a new snapmirror relationship?


I was thinking of doing this but wanted to get another viewpoint.


The main objective is to claw back the space savings and give back to the aggregate.  



Re: downsizing a volume

If you can use thin provisioning (you did not mention whether your volume/LUNs are thick or thin), you could simply disable space reservation on volume and LUNs, run space reclamation and wait until snapshots age off. Note that as long as snapshots exist space reclamation won't free any space for you.


If you must use thick provisioning the only way is to create new volume and Storage vMotion data there. You lose your existing snapshots in this case.


You cannot both keep snapshots and free space.

View solution in original post

Re: downsizing a volume

Ok understood


We use thin provison on both the Flexvol and underylying LUN.

Cloud Volumes ONTAP
Review Banner
All Community Forums