VMware vSphere ESXi 6.x
VMware vSphere ESXi 7.x
VMware vSphere ESXi 8.x
To prevent such accidental lost, use one of these options:
With file relocation:
.vmdk
file at the destination, effectively converting or cloning a raw LUN into a virtual disk. This also applies when the virtual machine is not moving between ESXi hosts. In this process, your original raw LUN is left intact. However, the virtual machine no longer reads or writes to it. Instead, the newly-created virtual disk is used.Note: If the RDM is shared between VMs as part of clustering solutions such as MSCS or ORAC, we need to remove the RDM disk from all the other nodes and retain it with the VM where migration task will be initiated.
If you want to clone a virtual machine without 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, only the RDM mapping file is deleted). Re-add them to the configuration when completed.
Notes:
When migrating Physical mode RDM pointer files that are greater than 2TB using Storage vMotion, you must use the vSphere Web Client.
Physical mode RDM data can be migrated to VMDK disks only through cold migration.
du -ah
command, you can confirm if the pointer exists in the directory on the alternate datastore.For more information on the various steps involved during the migration, see Migrating virtual machines .
For instructions on using Storage vMotion, see Migration with Storage vMotion.
Notes:
.vmdk
pointer files must reside on VMFS datastores. The NFS protocol does not support SCSI commands. For more information, see Unable to add a physical mode disk mapping (RDM) to a virtual machine stored on an NFS datastore.For Storage vMotion requirements and limitations, see the Storage vMotion Requirements and Limitations section of the vSphere Virtual Machine Administration.
VMware Skyline Health Diagnostics for vSphere - FAQ
Raw Device Mapping for local storage
Snapshots
Ensure that snapshots are committed before performing storage migrations, especially if you are removing mappings or disks from your virtual machine configuration and later re-adding them. During re-addition of the respective disk, the VMware Infrastructure or vSphere Client does not allow you to re-select a specific (the previous) snapshot level or .vmdk
file to add back to the virtual machine configuration.
Block size and capacity limitations of your destination datastore
Raw Device Mappings occasionally represent large raw LUNs. If you clone a virtual machine with an RDM still attached, the contents of the raw LUN mapped by the RDM are copied into a new virtual disk (.vmdk
) file at the destination. Converting an RDM into a virtual disk (.vmdk
) file does not succeed if your destination or target datastore does not have the capability of storing single contiguous files as large as the raw LUN. Large virtual disks have the same requirements or constraints.