topic Re: shrinking a LUN in Data Protection

shrinking a LUN

vehmaintl — Thu, 05 Jun 2025 07:24:58 GMT

storage: FAS31240

version : 7.2.5.1

volume: flexible

I am looking to shrink a lun, but when trying to do so with snap manager, it is greyed out.... Why is that ?...

Thanks

Re: shrinking a LUN

tanmoy — Sat, 08 Aug 2009 04:22:42 GMT

Hi David,

Normally LUN shrink is a rare operation and it makes sense to shrink a LUN when a large part of that LUN is unused over a period of time. Probably Snap Manager treats that LUN as a whole data file from application point of view; hence not allowing doing such operation.

Can you please share with us about the use case for LUN shrinking?

Thanks

Tanmoy

Re: shrinking a LUN

amiller_1 — Sat, 08 Aug 2009 04:25:18 GMT

If I'm not mistaken, LUN shrinking is only supported with Windows 2008.

Re: shrinking a LUN

tanmoy — Sat, 08 Aug 2009 05:06:12 GMT

As far as I know, Windows Longhorn was supposed to provide this LUN

shrink facility. We need to check this.

But if I understand properly, SDW 5.0 has a feature to reclaim space

from unused file system from ONTAP 7.2.1 onwards. This might work as

virtual LUN shrinking facility.

Thanks

Tanmoy

Re: shrinking a LUN

kutner — Mon, 10 Aug 2009 13:55:37 GMT

There are two separate features:

Shrinking -- only available with Windows 2008. This will let you actually shrink the size of the lun

Reclaim -- available with DOT 7.2.1+, will let you free up FAS blocks based on NTFS block usage. So if you wrote a 50 GB file in NTFS, then deleted it, you could reclaim the 50GB that ONTAP used within the lun.

Re: shrinking a LUN

mickehoe123 — Tue, 11 Aug 2009 08:27:29 GMT

You could try the LUN resize command from the cli also...... I would be very cautious of this though. I have done it in the lab.... but would I do it with live data... NO

Create a smaller lun if your heart is set on doing it and move the data into the smaller lun.

Mick