LUN Sizing consideration

[naveen1701]

I am looking for points to be considered for creating new LUN which needs to be presented to ESX server. Would like to know the points to be considered for LUN sizing and also there should not be any performance bottleneck

[srinivasvivek]

Are you planning to use iSCSI or FC? It depends on what array you are using at the back and also the storage layout. Remember to size for performance and capacity

[naveen1701]

its going to be FC SAN, i need to know the points which i have to tell the storage person for creating LUN for ESX server.Thanks

[bulletprooffool]

Naveen,

I'd simply size Luns based on the size of VMas and number I'd like on each LUN - I would suggest a target of no more than 15 - 20 VMs per Lun, so if Luns are 30GB, then I'd create Luns at( (15 or 20 x 30GB) x 1.2)

The additional 20% capacity is to allow fopr future growth / snapshots / reduced fragging etc.

If you are using thin provisioning, I would build a few sample VMs, determine actual size vs provisioned size and apply a similar sizing to the above - but would add about 35% as vMotion etc in ESX 3.5 can easily expand thin to thick disks, without you noticing,

Once you get to ESX 4.0 this will become easier to manage

[Shanuvashd]

The LUN size should not exceed More than 2 T.B as ESX supports a MAX LUN size of 2 T.B only.

1LUN=1PARTION=1 Datastore.

if you want to create a datastore of size more than 2 T.B you can do so by adding another LUN as an extent to the existing datastore.But it is not recommanded.

HP recommends using 8 - 16 VMs per LUN. If your VMs are not heavily impacting I/O, you may be able to exceed the conservative recommendations.

So based on this you can decide how many luns you want and you can tell your SAN admin to present them. Also make sure that LUN size does not exceed more than 2 T.B

If you find this info usefull consider giving points to me

[smudger]

Hi,

If you haven't already, it's worth checking out 2x articles which Duncan Epping (of Yellow Brick fame) recently published on LUN & block sizing. The links are:

Hope that helps.

Thanks, Neil

[Joshua_Mally]

Also consider a overhead of 2 GB per VM for VM files and log files.

Also each VM may create a Max swap file equal to the vMem assigned to the VM if no reservations are set. So a for 8GB RAM VM u might need 8GB more LUN space for the swap file creation.

If you found this information useful, please consider awarding points for "Correct" or "Helpful". Thanks!!!

-Josh

Trying to learn

[savantsingh]

Naveen,

You have to sit with your storage guy and discuss how does he carve LUNs right now.

It would be better if you guys can decide a standard as it is easier to manage storage that way.

The points you need to consider are what would be the size of your virtualised environment (size of the VMs) and what would be the possible growth you would expect in the near future.

What would you want your LUNs as .. i mean do you want vmfs partitions or do you wish to use RDMs (do keep the config maxs in mind)

If you different flavors of storage also try to present them as needed by Vms.

Hope these points help!!

Let me know if you have any other questions.