VMFS or Passthrough - for Windows 2012 Storage Spaces

[Jim82]

Dear community,

Running the latest ESXi 5.5, I'm not sure how to setup my storage.

I have the option of using an 8-port SAS controller as passthrough, directly to my Windows Server 2012 VM, running storage spaces. This option renders the controller unuseable for any other VM, than my 2012 server.

There fore I though about just making "normal" virtual disks(vmdk) and using those for Storage Spaces in Windows 2012. This would be more versatile as I could use all the drives on the controller for other VM's as well. However I can't seem to find any pros and cons about this option.

So I'm seeking the community's advice here, VMDK files or direct passthrough, for Windows 2012 Server with Storage spaces.

Thank you for any replies.

Best regards

Jim

[tomtom901 · Accepted solution]

I would always go with VMFS over DirectPath I/O (passthrough) unless there is a reason not to. DirectPath I/O offers a bit less latency / overhead but you offer up a great deal of flexibility that VMware can offer you. So in your case, when there is no specific requirement, I would go with VMFS. 64 TB VMDK's and WS 2012 are also supported in ESXi 5.5 so that won't be a reason to go with passthrough either.

Also note that when using passthrough, and you are running ESXi from that same controller (not via an USB stick or something like that), it might not even work or you can run into some strange problems. A colleague of mine once put an entire USB hub in passthrough mode, resulting into an USB keyboard not working anymore in the VMware console (DCUI). So I'd definitely watch out with configuring this.

[Jim82]

Thanks for your reply. I've decided to try out running VMFS only

BR Jim

[jnewman33]

Hi Jim-

Could you expand on your final solution.  I have Server 2012E R2 in a VM and several ESXi datastores that I would like to pass to the VM and then set up a storage space.  Just not sure how to do it.  I know this thread is old but you seem to be asking the same question that I have now.

Thanks,

James

[Jim82]

Hi James,

My final solution involved a battery backed RAID controller supported by ESXi 5.5. I'm now running only VMFS, no Storage Spaces, only normal windows shares, with virtual disks. I did this because of performance issues and flexibility.

My problem was that using a passthrough controller for a VM would cause it to be a "static" VM, without the flexibility ESXi offers.

Furthermore ESXi has very poor performance using local drives that are NOT cached. To my understanding ESXi does not offer write/read cache, which makes mechanical harddrives(non-ssd) extremely slow. At least that was my experience.

I dropped Storage Spaces, because it makes no sense running a RAID10 -> VMFS -> Storage Space solution. Storage Spaces only works well if the drives are non-RAID, passed directly through to W2K12, so you can take advantage of the flexibility that Storage Spaces offer(mixing raid levels on the same drives).

Hope this helps

/Jim

[jnewman33]

Jim-

Thank you for the timely, thoughtful and informative reply.  Based on the information I have a new question I hope you can answer.

I am now going to change my hardware to include an ESXi approved HBA either add in or embedded.  Once done can I use the HBA attached drives in my VM's and keep the flexibility to use Vmotion etc?

Thanks again,

James

[Jim82]

Hello James,

You are most welcome!

I believe that best vMotion practices requires the storage to be "central". I think you're limited to the below options:

A) Have a centralised storage infrastructure ie. SAN/NAS

B) Take advantage of the new vMotion starting from ESXi 5.1 I believe that you can actually migrate VM's using only local storage, but the destination must have it's own local storage with enough space for the VM(s). You must use the web client for it to work properly though.

BR Jim