topic Resizing LUN with System Manager in VMware Solutions Discussions

Resizing LUN with System Manager

stanleyj42 — Thu, 05 Jun 2025 06:50:35 GMT

Hello Everyone,

I'm fairly new to the storage game and wanted to ask a few questions just for reasurance before i go resizing LUNS that are currenlty in use.

We just setup a FAS3270 running 8.0.1P3 7-mode that is attached to a UCS Vsphere 4.1 environment. I carved out a 2tb flexvol with a 1tb LUN used for the vmware datastore. Well that was poorly planed because within the first month of moving servers to the new system we have quickly eaten up that 1tb.

My real concern being so new to the storage world is can i just go into the system manager and changed the LUN size from 1tb to 2tb on the fly? I know NetApp is famous for its resizing abilities but Im just uncoformtable changing the size with the LUN currently in use.

I have read all over the place that its ok and safe to change especially with VMware attached LUNs but i would just like to consult the oh so wise community before doing so.

Thank you.

Resizing LUN with System Manager

radek_kubka — Fri, 15 Jul 2011 12:41:59 GMT

Hi,

It is safe providing you don't fill up the volume completely - so definitely your LUN should be smaller than your volume.

You may consider thin provisioning of the volume (set guarantee to none), growing it to, say, 3TB & then growing the LUN to 2TB.

Bear in mind you also need to expand your datastore on the vSphere side (unlike with NFS datastores).

Regards,

Radek

Resizing LUN with System Manager

stanleyj42 — Fri, 15 Jul 2011 12:58:09 GMT

Thank you Radek. This makes me feel much better.