Shared Cluster VMs Fail to Power on After Virtual Disk Resize.

Products

• VMware vCenter Server

Issue/Introduction

Symptoms:

• You may not be able to power on the VMs using shared disks as you may see an Error: VMware ESX cannot open the virtual disk "/vmfs/volumes/######/VMname/VMname.vmdk" for clustering. Verify that the virtual disk was created using the thick option.

Environment

VMware vSphere ESXi 8.x

Cause

The shared virtual disk is incorrectly extended/resized on a secondary or tertiary cluster VM instead of the designated primary cluster VM.

Resolution

Pre-Checks:

1. Take a backup of all involved VMs.
2. Note down the current SCSI controller settings, SCSI number and SCSI ID to which every Disk is connected, as the disks will need to be attached to the same SCSI ID when they are attached back once the migration is complete
3. Record the datastore paths of disks.

Procedure to follow:

1. Shutdown/Stop the cluster application gracefully by following all the required vendor best practices
2. Shut down all VMs that are sharing the VMDKs (First shutdown all the secondary/passive VMs and then primary VM)
3. Remove the problematic shared VMDKs from the secondary/tertiary VMs (choose Remove from VM only, not delete from disk)
4. Then remove the VMDK from Primary VM (choose Remove from VM only, not delete from disk)
5. Attach the VMDK to new Primary VM. (Please pay attention to do that reflecting same SCSI number and ID to which every Disk is connected as noted in the Precheck)
6. Attach the disks to secondary/tertiary VMs using add existing hard disk option. (Please pay attention to do that reflecting same SCSI number and ID to which every Disk is connected as noted in the Precheck)
7. Power On the VMs starting with Primary/Active Node before powering on the secondary/passive.