SQL Cluster VMs with Shared RDMs Fail to Power On

Products

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

Issue/Introduction

• VM nodes of SQL clusters are moved to same host
  
  
• VMs Fail to Power On with error "Unable to access file /vmfs/volumes/UUID/VM_Folder/VMname-rdmp.vmdk since it is locked /vmfs/volumes/UUID/VM_Folder/VMname-rdmp-flat.vmdk"
  
  

Environment

VMware vSphere 8.x

VMware vSphere 7.x

Cause

VMs in SQL clusters, utilizing shared RDMs with physical SCSI bus sharing, cannot power on if more than one VM migrated to or started on the same ESXi host. This triggers a "locked" file access error: "Unable to access file /vmfs/volumes/UUID/VM_Folder/VMname-rdmp.vmdk since it is locked /vmfs/volumes/UUID/VM_Folder/VMname-rdmp-flat.vmdk"

Resolution

To ensure the successful power-on and operation of all SQL cluster VMs, each node of the cluster must be placed on a different ESXi host. This configuration is widely known as "Cluster Across Boxes (CAB)," where the virtual machine nodes are distributed across distinct physical hosts, thereby preventing RDM access conflicts.

Additional Information

Reference:
Microsoft Windows Server Failover Clustering (WSFC) with shared disks on VMware vSphere 8.x: Guidelines for supported configurations