How to Shrink a Volume on Equallogic SAN

Question

I extended a disk on a DB server (so we could temporarily restore a database) and I would like to shrink the volume back down now that the data has been deleted.

I deleted the data and shrank the disk within the OS which freed the space on the windows volume, but the space is not shown as released for the volume in the SAN management GUI. If you try to modify the volume size, it warns that the "new volume size is less than current use".

Is it possible to release the space on the SAN volume or am I stuck with it at this size?

Environment

The DB server is Windows server 2008 running on VMWare ESX 4.0

The disk to shrink is a mapped raw LUN, the volume is on a Equallogic PS6000 (firmware V5.0.7)

Solution 1

Go to Group Manager command line interface (CLI) then:

volume select vol_name shrink new_size [parameters]

The sizes are assumed to be in megabytes, so unless you specify the specific suffix it will default to megabytes.

Variables and Parameters can be found here.

Solution 2

While the shrink command works to shrink the volume, no data will be available on the volume after the shrink. Windows sees the volume as RAW, unformatted. Access the snapshots, specifically the snapshot that was created when the shrink command was issued, to copy data to the newly shrunk and formatted volume. As with any operation where data is involved: Ensure you have a backup before attempting this.

Comments

[Chris]

Thanks for the input; the note concerns me: "Be careful when decreasing the size of a volume. It is possible to decrease volume space to less than what is currently being used." How do I ensure that there isn't something being used that I'm not aware of?

[Giordano Ferrari]

@Chris I would double check the size on the VMware side (from the ESX level) that should give you a clear indication of how much storage you're using. Shrinking any type of storage - you really want to be careful.

[Chris]

I still have some concerns, but it looks like that's the Equallogic way to do it, thanks.

[Chris]

I did not. It's not a critical server so if I need that space I'll delete the volume and recreate, especially in light of your comment.