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JulianMilano
Contributor
Contributor

Where's the RDM gone?

I have a situation where I have an RDM disk from an EMC VNX SAN connected to a Windows virtual server running on VMware 6. From my knowledge of RDMs, they use pointer files on the datastore (usually stored with the virtual server) which point to the actual LUN from the SAN. I've found that if I delete the RDM from the virtual server, using the "delete-from-disk" option, I can no longer find that RDM on the other hosts of the cluster. But if I open the virtual server where the RDM used to be connected and search the available list for the WWN of the LUN, it is there.

Is this normal behaviour? How do I find the RDM on the other hosts to attach to other virtual servers?

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kastlr
Expert
Expert

Hi,

the "delete from disk" option removes the pointer file(s) from the VM folder, but doesn't wipe the content of a p/vRDM.

So you should have a VNX LUN which does contain a NTFS partition.

You should be able to verify this using the following command.

partedUtil getptbl /vmfs/devices/disks/naa.6006xxxxxxxxxxxx

The following article describes how to recreate the missing pointer file.

Recreating pass-through Raw Device Mapping (RDM) files for a virtual machine (1026256)

Regards

Ralf


Hope this helps a bit.
Greetings from Germany. (CEST)
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cyberfed2727
Enthusiast
Enthusiast

Are you talking about moving an RDM to a different VM? If so you would follow this basic process:

1. Remove/unmount from the OS level (Windows - Disk management --place off line for example)

2. Remove the disk from the VM (edit VM settings remove the RDM disk as a device)

3. Next add a new disk (edit vm settings) to the other VM, add as RDM.

4. Present/mount the disk within the OS of the VM.

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