RDM question.

[mauriciomor3]

I have two questions regarding RDMs.

My client has no backup solution yet, and many VMs (all Windows) with two hard disks wrongly created like that:

C: (virtual hard disk)

E: (RDM hard disk, physical compatibility mode)

So I need to remove the RDM hard disk.

My first question is:

Since they have many others wrongly created VMs with several hard disk RDMs, would be a trouble to remove those RDMs from it? I mean, until now they didn't have any problems with those machines, so probably would be OK to remove it without have any data lost from other machine. Please comment this problem OK?

My second question is:

I have to backup those machines before to do anything.

I noticed that the snapshot option it is not enable in those machines that has RDMs (when they are turned on, I don't know about when they are turned off)

So does anybody knows if I just copy all the files (VMs turned off) from

/vmfs/volumes/VMFS01/Machine1

to some other place, remove RDMs and if I got any problems later on, I would just put the files back in again...

I don't know if that would work, and because I don't have how to test it, I would like some answer to help me out with this trouble.

Thanks in advance.

[jccoca]

Hi,

Snapshots are only supported in RDM disks in virtual compatibility mode. If you remove a RDM disk from a VM, why do you think you can lost data from other VMs?

RDM is a mapping to a LUN, if you remove the mapping you don't lost the data and you can recreate the mapping. And what do you want to do with the data in those disks? If you want to preserve in a virtual disk you can import it with vmkfstools and then change VM disk config to the new disk.

[mauriciomor3]

"If you want to preserve in a virtual disk you can import it with vmkfstools and then change VM disk config to the new disk."

When you say that, do you mean it is possible to "recreate a new disk" and preserve all data on it ,and just change the type and size of disk? Like in this case, where I need to remove "E:" witch is a RDM and recreate, a different disk (virtual disk) with this vmkfstools?

If so would you tell me how, or recommend a good documentation about it?

Now they have:

"E:" RDM 250 GB

They nedd:

"E:" virtual disk 600 MB

Tanks.

[jccoca · Accepted solution]

Yes you can create a new disk preserving all the data, but the new disk will be of the same size as original disk. If you want to increase capacity you can use:

vmkfstools -X 600GB diskname.vmdk

If you want decrease capacity I think that the best solution is to create a new disk of desired capacity 600MB mount this new disk into the VM and then from insite the VM copy the data to the new disk and then remove the RDM.

To import a disk you can use:

vmkfstools -i olddisk.vmdk newdisk.vmdk