VMotion RDM's.

[Rohail2004]

Can I VMotion a VM which has RDM's attached to it? what is the best way to move those VM's?

[msemon1]

Cold Migration. I ran into this issue trying to do a Storage VMotion. So I guess that begs the question is there a way to Vmotion or migration VM's with RDM's without powering them down?

Mike

[Rohail2004]

That's what I thought. Cold Migration, but since I have never done it so I thought to get some advice, but after the cold migration all the RDM's will be intact properly?

[Jakobwill]

When you choose to do a cold migration, you can disconnect the RDM while moving og reconnect it again after.

But i would recommend doing a cold migration and then you selectwhere to place the disks, select advanced there you can take one disk at a time.

If you RDM is a Virtual RDM you must remember to move the vmdk file when disconnecting it.

[msemon1]

Also document the storage your RDM's are connected to in case you need to recreate.

[Rohail2004]

My RDM's are physical....

[ian4563]

Yes, you can Vmotion a VM with RDM disks as long as the host that you're going to Vmotion to can see the RDM. We have several large file servers with RDMs and Vmotion them all the time, never had any issues. Vmotion validation would probably fail anyway if the destination host couldn't see the RDM lun so there's probably little risk in trying if you are unsure.

[msemon1]

So are you saying you can Vmotioning VM's with RDM's physical or virtual compatibility mode as long as both hosts can see the LUN? So then the only stipulation is they have to be powered off and done by cold migration.

[Rohail2004]

I thought you can't VMotion RMD's? so you are saying I can as long as LUN's are available to both hosts?

[vmroyale]

Hello.

"Think of an RDM as a symbolic link from a VMFS volume to a raw LUN (see Figure 8‐1). The mapping makes LUNs appear as files in a VMFS volume. The RDM, not the raw LUN, is referenced in the virtual machine configuration. The RDM contains a reference to the raw LUN.

Using RDMs, you can:

- Use VMotion to migrate virtual machines using raw LUNs."

This is quoted directly from the p.146 of the ESX Server 3 Configuration Guide (Update 2 and later for ESX Server 3.5 and VirtualCenter 2.5). Chapter 8 is devoted entirely to Raw Device Mapping.

Good Luck!

[msemon1]

Thanks for clarification. It appears you can VMotion RDM's. I thought under some circumstances you could Svmotion RDM's (small RDM's) maybe not. Powering them of is probably safest.

Are raw mapped LUN's considered the same as raw device mapping? I think people use them interchangeably. Perhaps mistakenly I thought RDM's in physical mode were mapped raw

LUN's and those in virtual mode were raw mapped devices. Is this just semantics?