LUN limitation on FS6080?

[eilirw1974]

Is there a maximum LUN size limitation that can be created on a filer FAS6080 running Data ONTAP 7.3.3? I am trying to create a 2Tb LUN using SnapDrive 6.2.1 on a Windows 2003 SP2 (64Bit) Standard Edt within a created 2.5Tb volume.

Can anyone help? Im not sure what I'm doing wrong!!

[aborzenkov]

I am not aware of any limits imposed by NetApp. Host could be limiting max supported LUN size though.

You did not explain what did not work for you. Could you give more details what you have done and what was the result?

[eilirw1974]

When I'm trying to create a new disk from SnapDrive for Windows and during the wizard the maximum lun size presented is around 1Tb LUN. The initial volume has been created around 2.5Tb, of which 20% is reserved for snapshots, so which should make available 2 Tb for a LUN?

[shaunjurr]

Hi,

You are probably running into limits because of fractional reserve and space reservation.  Ideally, thin provisioning is going to save you lot of such headaches.

1. Create your volumes with guarantee=none

2. Turn off snapshot reserve.  No need to reserve space, really.  If you have enough space on the volumes, you can take snapshots. Easy.

3. Turn off snapshot schedule "0 0 0".

4. Create your LUN's with reservation=none

5. Setup vol autosize to increase your volume size or, alternatively/in combination with snap autodelete.

Then I think you can create 16TB LUN's...  Just always make sure you monitor the capacity of your aggregates.  Keep them under 90%.  This way you basically have one "fire" to put out instead of having to balance a bunch of different settings.  There's a TR on Best Practices for Thin Provisioning as well.  A good idea to read it.

Good luck.

[aborzenkov]

There is checkbox “Do you want to limit the maximum disk size to accommodate at least one snapshot?”; if it is enabled (default), SD tries to additionally reserve 100% of LUN size for possible snapshot creation. If you are not going to create any snapshots, you can uncheck it.