File Server Data Volumes - RDM's or VMFS?

[tostao]

Folks,

I'm using vSphere Enterprise Plus 4.1.

I've read up on the RDM's v VMFS debate. However, the arguments for VMFS seem to assume you are planning to run the operating system from the volume. In this case VMFS wins.

I have a VMFS volume set aside for a couple of my operating systems already. But one of the VM's will be a file server. I'm planning to add 7 x 500GB LUN's to this VM. I don't plan to make snapshots of these volumes.

It seems there is very little to skew the argument one way or another in favour of either storage type. In the absence of any compelling reasons, I'm slightly siding with RDM's. It will give me more flexibility to 'swing' the storage if I ever need to upgrade and I won't get the red exclamation marks appearing in vCenter like I would by filling up my VMFS volume with a virtual disk file.

Can I ask for some advice on what would be a 'best practice' for adding volumes which will just be used to store data?

Regards,

Michael

[Yattong]

Hey,

To be honest, you really could go either way...

Have you read this? http://www.vmware.com/files/pdf/performance_char_vmfs_rdm.pdf

Both VMFS and RDMs will have their pos and cons, you just have to decide which suits best to you're needs.

e.g. you may need to decide which one will give you the most flexibility within your own environment.

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~y

[Xeonel · Accepted solution]

From a management perspective I'd go for RDMs, especially if it's going to be a file server.

Let's look at some arguments. If you're going for VMFS, it means that all the IO to the fileserver would be shared with the rest of the VMs residing on the datastore (which, depending on your setup could be ok). RDMs also offer the advantage of being able to migrate to physical at some point if workload increases beyond the point where it makes sense to have a VM.

Also, I wouldn't go all way on RDMs, just for the data volumes. So OS goes on VMFS while everything else on RDM. Don't think to much about performance, as lately differences between VMFS and RDMs are negligible.

[amvmware]

As Yattong has indicated there are pros for both ways of doing it - they things that may point you in a particular direction is the backup strategy for the data and any future strategies you may have in terms of replicating the VM as part of a DR strategy and what that may involve, ie SAN snapshots ..etc