How to re-add RDM (physical)

[bulabog]

Hi All,

Had some problems migrating a VM to another host - turned out to be due to it having RDM (physical) disks. So shutdown the vm and migrated it offline and was successfully migrated - but now, I could no power it on as it was complaining about disk not found. So I edit the VM and removed the RDMs (leave the disks) so that I could then re-add it. However, I could not add RDMs now as it is greyed out (from the Add new hard disk wizard).

When I looked at the datastore, I see the RDM files (pls see attached screenshot) - question is, how can I add them back to the VM?

Many Thanks.

[weinstein5 · Accepted solution]

From the new host are you able to see the Raw LUNs? The RDM in essence is a special VMDK that is nothing more than a pointer to the RAW LUNs and if the new host can not see the raw LUNs then you will not be able to access them from the VM on the new host -

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[AndreTheGiant]

A RDM disk can be readded in the same way you create a new one.

As written before check if you can see the RDM LUN from the host (Configuration / Storage Adaptaters).

Then add the LUN to the required VM as a RDM disk.

Andre

[Matt_B1]

Whenever I remove a RDM, I always select to remove and delete files. This help keep my storage clean of unused RDM mapping files. To add RDMs back, I simply go to add a RDM as a new disk. I select the RDM from the lists of LUNs just like the original time. The RDM data remains intact and untouched during this whole process. The only time you want to consider keeping RDM mapping files is if you have Microsoft clustered VMs that share storage.

[bulabog]

Hi All,

This may seem strange - but after restarting the host, all was good. The disks were locked for some unknown reason.

Thanks for your helpful answers.

Cheers.