Best practice SAN sizing for vMotion

[TheTechie]

Hi,

I currently have 3 ESXi 4.0 hosts that have about 40 VMs stored on local datastores which I am going to move to a EqalLogic SAN and would like some help with volume planning. The SAN will have just over 2TB free and right now the VMs are only using about 900GB.

My intention is to upgrade to Essential Plus (currently just have Essential) and utilize the VMotion which I believe require shared datastores. Is it best to create just one large volume on the SAN to store a Datastore with all the VMs or multiple volumes? I read in another thread that with ESXi v3 it was best to only use up to 500GB but I’m not sure if that still true.

Also EqualLogic puts spreads the volumes across all disks so I can’t configure separate volumes on separate disks. I’m also looking at using eventually using Veeam backup if it helps with planning.

Thanks for any help.

[aldikan]

Hi,

I would create 2x1TB datastores and choose 4MB block sizes,

or alternatively,

3 datastores: 1x1TB (4MB block size) and 2x500GB (2MB block size).

I would not not go with single datastore, unless it is going to have VM with very large partitions. However it is acceptable scenario as well.

Alex

[vmroyale]

Hello.

I currently have 3 ESXi 4.0 hosts that have about 40 VMs stored on local datastores which I am going to move to a EqalLogic SAN and would like some help with volume planning. The SAN will have just over 2TB free and right now the VMs are only using about 900GB.

The maximum LUN size is 2 TB - 512 bytes, so you are looking at having at least two LUNs for starters.

My intention is to upgrade to Essential Plus (currently just have Essential) and utilize the VMotion which I believe require shared datastores. Is it best to create just one large volume on the SAN to store a Datastore with all the VMs or multiple volumes? I read in another thread that with ESXi v3 it was best to only use up to 500GB but I’m not sure if that still true.

vMotion does require shared storage. As stated earlier, due to the max LUN size you will have to present two "LUNs" (really TARGETS in EqualLogic, but I digress) to your cluster. You could use extents and create one large VMFS volume, but I wouldn't recommend that approach. Also, with the latest version of the EqualLogic firmware you will get the VAAI Hardware-Assisted Locking. A lot of the reason around creating multiple datastores is to avoid issues with VMFS reservations, but with the EQ and the VAAI Hardware-Assisted Locking this is going to be less of an issue. I would personally just carve it up into two equally sized volumes (in EQ speak) and then present each of these as datastores to vCenter.

Good Luck!

[AndreTheGiant]

See also:

Andre

[jcwuerfl]

You'll want to create several smaller Datastores but be consistant and make them the same size. aka 3x500gb or 3x600gb may work pretty good then spread the VM's on the LUN's according to their activity. Pairing heavy IO VM's with Lighter IO VM's is a good practice if possible. You will also want to understand the block size and what the largest VM size will be. 1mb=256gb, 2mb=512gb etc.

[malaysiavm]

you should also consider the number of VM you plan to have per LUN which will impact the overall performance of the virtual machines. Sizing wise, you should consider the average virtual machine size and the maximum size of the VMs you have

Craig

vExpert 2009 & 2010

Malaysia VMware Communities -

[TheTechie]

Thanks for the feedback, I'll probably create 3x 500GB LUNsto start with and keep the distribution similar to how we distribute it now across the three servers since we don't have any disk performance issues. I checked and we average about 15-25GB per vm with a few as low as 5 or high as 50GB.

Thanks again.