Expand an RDM LUN of a VMware VM

Ensure that there are no snapshots on the disk before attempting this operation. If there are snapshots present, commit them. Otherwise, you may experience data corruption Steps to expand RDM in Physical Compatibility Mode In the vSphere client, select the VM which you want to extend the disk, Edit Settings and check the disk whether it’s a Physical or virtual compatibility mode. 1. If it’s a physical compatibility mode, Good news is no need to do anything from the VM side. No down time required of VM 2. Expand the RDM LUN from the SAN Side – Performed by Storage team 3. Re-Scan the HBA’s at ESX host ( Configuration Tab -> Storage Adapters -> Rescan on top right) and see the new LUN Size is observed 4. Now go to the VM and open Disk Management, you should see extra space available as Unallocated, if not means it’s not expanded properly or require rescan of HBA adapters 5. Open disk part / Ext part utility and extend the available space. Steps to expand RDM in Virtual Compatibility Mode 1. Shutdown the VM and remove the RDM from the virtual machine. Before removing, make note of SCSIX: Y position from VM settings. 2. Expand the RDM LUN from the SAN Side – Performed by Storage team 3. Re-Scan on the ESX and verity the new LUN size is expanded. 4. Recreate the RDM Mapping. Go to VM -> Edit Settings -> Add Hard Disk -> select RDM, then select the same position we noted above for SCSI 5. Start the VM and check in Disk Management 6. Use disk part utility to extend the added space Testing & Confirmation In My Computer, confirm that the desired drive is expanded.