topic Re: ? Recovering snap reserve space for a LUN in Data Protection

? Recovering snap reserve space for a LUN

ThomasBebee — Thu, 05 Jun 2025 07:33:03 GMT

I created a volume with the default of 20% snap reserve. In the volume I then created a LUN and it properly showed the amount space available, taking into account the 20% set aside for snap reserve. The LUN showed up properly on a Windows client once it was mapped. I then went and set the snap reserve to 0 and on the controller, the space available changed accordingly (more space now available).

However, the mapped drive on the Windows client continues to show the original space available. I tried several things in an attempt to get the mapped drive from the Windows client to recognize the additional space for the LUN. In the end, I removed the LUN and recreated/re-mapped it, which did work as expected - seeing the new additional space.

Is there any way without deleting/re-creating the LUN, to get the Windows client to acknowledge the increase in space available?

No SnapDrive involvled.

Thanks.

Tom

Re: ? Recovering snap reserve space for a LUN

kusek — Wed, 22 Oct 2008 21:07:17 GMT

What you are seeing is indeed correct.

Let me know if this example describes your situation, and perhaps the misunderstanding.

I create a 100gb lun on a 200gb volume.

The filer shows: 100gb in use, with 60gb avaliable and 40gb available in Snap Reserve

From the Windows host, I show 100gb available in my lun.

If I were to go increase or decrease my Snap Reserve, the amount of space available in my volume will indeed change (to be more or less)

However, within Windows and within the LUN the amount of available space will remain the same.

The lun is only as large as the space you specified, and will remain that maximum size usable (100gb lun will only ever show 100gb max available space in windows) - Regardless of the size of the volume it sits on.

At which point, if you want to increase the size of the lun, you can use the lun resize command, and manually extend the LUN within Windows.

Hopefully this helps with what you're doing Thomas,

Christopher

Re: ? Recovering snap reserve space for a LUN

ThomasBebee — Thu, 23 Oct 2008 18:28:58 GMT

Christopher,

Thank you for the explanation. I followed your example and was able to accomplish what I was trying to do.

Tom