LUN - Recommended free capacity per LUN?

[Eire09]

Hi,

What is the recommended size of free LUN capacity that should be left available per LUN?

Thanks in advance,

Peter

[UmeshAhuja]

Hi,

Very informatory link as per your query.

http://www.gabesvirtualworld.com/storage-how-to-size-your-luns/

[continuum]

that depends on many factors

do you use thin provisioned VMs ?
do you use snapshots ?
do you run automatic backup-tools ?

the formula I use for LUNs that use thick provision and no snapshots is

for every VM that usually runs on that LUN sum up its vRAM + 1 Gb

so if you have 10 VMs using 4 GB of vRAM the result would 50 Gb as the minimum required free space - enough to suspend each of them in an emergency.
If you use snapshots or thin provisioned VMs you of course need more than that

[Eire09]

Thanks for your reply.

We don't use Thin Provisioned LUNS

We use Snapshots & our backup solution is Netbackup that uses Snapshots. 

How do I work out how much free space is needed in this case?

Thanks again.

[continuum]

the idea is to survive at least one day ...
so assume your backup-tool runs amok and does not clean up the daily snapshots
do a rough calculation of the space required for such  a scenario and add that to the value you need for a emergency suspend of all VMs