VM will not boot after storage vMotion to new SAN

Products

• VMware vSphere ESX 5.x
• VMware vSphere ESX 6.x
• VMware vSphere ESX 7.x
• VMware vSphere ESX 8.x

Issue/Introduction

Symptoms: 

• A VM was recently migrated to new SAN
• When rebooting the VM (post migration), the VM is stuck on the starting screen:

• The VM has physical mode RDM's

Environment

• VMware vSphere ESXi 5.x
• VMware vSphere ESXi 6.x
• VMware vSphere ESXi 7.x
• VMware vSphere ESXi 8.x

Cause

• The VM has physical mode RDM's that are no longer available.  For example: the SAN was turned off, disconnected, unzoned, or the LUN itself was unmapped from the ESXI hosts. 
  • To verify,  see KB: Identifying Virtual Machines with Raw Device Mappings (RDMs)

Resolution

• Replicate the LUN to the new SAN from the array side, if possible (if the arrays are interconnected).
• Otherwise, you can migrate the data to a newly presented LUN from the new SAN.  See KB: How to migrate a RDM backed disk to a new storage array

Additional Information

• When a VM with physical mode RDM is sVmotioned to a new datastore, the VMDK descriptors and RDM mapping files for the physical mode RDM's are migrated, but the VM will continue to use the RDM from the original SAN. See KB:  

Migrating virtual machines with Raw Device Mappings (RDMs)