Raw Device Mapping Questions

[Borat_Sagdiev]

Hello all, a co-worker of mine had some questions that I would like to assist him with:

How do you make the RDM (Virtual) appear to the Virtual Machine as a Storage connection?

Can you increase the size of the LUN that the RDM Pointer is connected to and have it reflected to the VM without bringing down the VM? On the fly increase?

Can you transfer RDM from Physical to Virtual machines?

Thanks in advance!

[esiebert7625]

Here's a good doc on RDM's...

ESX Server Raw Device Mapping - http://www.vmware.com/pdf/esx25_rawdevicemapping.pdf

[formulator]

I don't really understand the first question.

Yes, if your storage array supports it and your OS supports it.

Yes, just present the LUN to the ESX server that will host the VM (if you have multiple hosts with vmotion make sure you do all ESX hosts) instead of the previous physical box.

RDM is just a small file that you add to the VM as a "Disk" that points to a raw LUN on your storage array.

[tgradig · Accepted solution]

Yes you can transfer RAW disks from Virtual to Physical.

To increase the RAW disked from a LUN, we had to attach the RAW disk to a physical server grow the disk and then reattach it back to the Virtual Guest.

If you just grow the disk on the SAN, ESX would see it as an extended part. Does anyone know how to combine those so you don't have to un-attach from the virtaul guest.

[formulator]

You just grow the LUN on your storage array, windows will then see the disk as having free space at the end of the disk.

After that you just use diskpart to grow the partition or create a new partition. I've done it a few times on VM DB clusters without issues.

[denizmis1]

Hi There,

In my config, the windows VM has 2 hard drives:

Disk1) Boot virtual disk (vmdk) (C Drive)

Disk2) Data disk (raw device mapping to LUN on SAN) (F Drive)

Do I need to shut down the Windows VM before growing the LUN on the SAN which is the HDD2 above?

The Raw Mapped LUN is not the boot partition of my VM, but it is an additional data partition of the file server.

Many thanks

Deniz

[davieb1969]

I didn't think that was true for a mapped raw LUN.