Separate OS VMDK from Data VMDKs

[jim33boy]

Hi all,

I have an HP P2000 G3 iSCSI SAN providing storage to a 5 host Vsphere 5 cluster. I have 4 Vdisks configured, 3 of these are RAID 5 and one is a RAID 10. From these I am provisioning 2TB datastores to my ESXi cluster.

I have a VM that will run a database application and this application suggests that the DB file system and the after image file system be on different disk sets. The database filesystem must be stored on RAID 10. These recommendations are obviously for physical hosts so I am not sure how to configure in a VMWare scenario. With a physical host we usually have an array and chop 2 disks for a RAID1 OS mirror, 2 disks for the after image data, and the remaining disks configured in a RAID 10 for the database filesystem.

So my question is this.. In a VMWare environment, is it suggested to keep the OS VMDK on one datastore sitting on an underlying RAID 5 lun, the after image VMDK in another datastore on an underlying RAID 5 lun, and finally the Database VMDK on yet another datastore on an underlying RAID 10 lun? Or is it suggested to keep the VM and all it's VMDK's within a single LUN? The RAID 10 is sitting on 12 10k SAS disks so the IOPS requirements should not be an issue.

I had read that even putting VMDK's on separate datastores in general is not recommended because it may cause issues with SVmotion Storage Vmotion.. Can anyone confirm that?

Thank you

[weinstein5 · Accepted solution]

Welcome to the Community - There should be no issue seperating the VMDKs on to different datastores - since the performance characteristics of the undrlying storage is passed to the virtual disk it is best practive to place virtual disk on datastores with the required RAID set/performance -

I do not know of any issues in regards to storage vmotion with VMs spread across multiple datastroes -

[EdWilts]

The "issue" with storage VMotion is that by default, it wants to put all of the VMDKs in the same datastore.  You'll need to use something like storage profiles or advanced options in storage vmotions from undoing what you've done to separate the VMDKs.

There are a lot of good reasons to keep the VMDKs separated but managing that can be a pain.

[rickardnobel]

jim33boy wrote:

I had read that even putting VMDK's on separate datastores in general is not recommended because it may cause issues with SVmotion Storage Vmotion.. Can anyone confirm that?

I agree with the above. The only issue should be that you will have to remember to select "Advanced" when (if) doing a storage vMotion of this VM.