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How to move a physical rdm pointer file?

Hi everybody,

we 're currently installing virtual mssql Cluster Systems on vSphere 5.5 in CAB (Cluster across boxes) configuration

The Clusters are already installed and we used physical rdm Disk for the shared Cluster data.

The rdm's pointer files are placed in the Directory of the Clusters first node.

After some internal discussion, we plan to seperate the rdm pointer files from the first nodes vm files.

The pointer files should be moved to a seperate datastore Directory structure /ClusterDisks/<clustername1> etc

The plan is to power down all Cluster nodes, remove all the shared harddisks from the cluster node VM's, move the rdm file to a the new location and assign the disks back again from the new location to all VM's

When I opened the datastore browser I can only see the disk as vmdk (what seems to be ok), but when I try to move this file, it is converted to a real vmdk.

So my question is: Is it possbile to move the pointer file ?

Best regards,


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2 Replies
VMware Employee
VMware Employee

I can confirm below statements:

These are just some highlights: from below blogs:

  • Raw LUNs themselves cannot be moved, as they are raw disks presented from the SAN. However, the pointer files (RDMs) can be relocated if required.
  • Note: Deleting the mapping file or descriptor file for the RDM does not affect the data
  • If you wish to cold migrate a virtual machine without cloning or converting its RDMs, remove them from the configuration of the virtual machine before migrating. You can delete the RDM from the disk when removing it (the raw LUN contents are not changed). Re-add them to the configuration when completed.

Reading below blogs can answer your query:

VMware Technologies Blog: Raw Device Mapping (RDM) DeepDive


VMware KB: Recreating pass-through Raw Device Mapping (RDM) files for a virtual machine

Thanks & Regards
Vikas, VCP70, MCTS on AD, SCJP6.0, VCF, vSphere with Tanzu specialist.
Disclaimer: Any views or opinions expressed here are strictly my own. I am solely responsible for all content published here. Content published here is not read, reviewed or approved in advance by VMware and does not necessarily represent or reflect the views or opinions of VMware.


You can use storage vmotion to move the RDM vmdk files.

You just have to select migrate then change storage and there you click on the advanced button. When in advanced mode you can individually migrate the disk files as you want and leave the system disk where it is.

this article can be of use if you run into performance issues

VMware KB: ESXi/ESX hosts with visibility to RDM LUNs being used by MSCS nodes with RDMs may take a ...

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