Unable to use Snapshots or perform a backup on virtual machines configured with bus-sharing

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

When working with a combination of Raw Device Mapping (physical or virtual), Microsoft Clustering (MSCS), Snapshots, Consolidated Backup, and/or Data Recovery, the following symptoms can occur:

• Cannot take a snapshot
• The snapshot feature does not appear to be available on virtual machines and the option is greyed out
• When attempting to set a SCSI controller to shared, the following error may appear:

Device 'SCSI controller 1' is a SCSI controller engaged in bus-sharing. 

• When attempting to create a snapshot, the operation may fail with the error:

Snapshot creation failed: Virtual machine is configured to use a device that prevents the snapshot operation: Device '' is a SCSI controller engaged in bus-sharing. 

Environment

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

Cause

Consolidated Backup (VCB), Data Recovery (vDR), Microsoft Clustering (MSCS), Snapshots, and Raw Device Mappings(RDM) all have their own limitations and requirements that need to be adhered to. The following are a list of requirements:

• VMware Consolidated Backup requires the use of snapshots to create a backup.
• VMware Data Recovery requires the use of snapshots to create a backup.
• Microsoft Cluster nodes that exist across different physical hardware require virtual controllers to be in bus sharing configuration.
• Snapshots of a Microsoft Cluster node virtual machine using the Microsoft iSCSI Initiator to connect to storage is not supported as there is no connectivity with which to create said snapshot on such a disk.
• Snapshots are not supported on Physical mode Raw Device Mappings.
• Snapshots are not supported on disks connected to controllers configured for bus-sharing configuration.

Based on the above limitations, we can make the following conclusions:

• Microsoft Clustering requires bus-sharing and therefore cannot be used in conjunction with use Consolidated Backup, Data Recovery, or Snapshots.
• Virtual machines with a Raw Device Mapping in physical mode cannot be used in conjunction with use Consolidated Backup, Data Recovery, or Snapshots.

Resolution

Workaround:

If you require bus-sharing:

• Consider running backup software within your guest operating system as an alternative solution.
• If your virtual machine currently has snapshots and it is preventing you from configuring bus-sharing, delete the snapshots. 
  
  Note: If snapshot consolidation fails, see Consolidating/Committing snapshots in VMware ESXi

If you do not require bus-sharing:

• If your virtual machine is currently configured with bus-sharing, but you want to create snapshot, you must disable bus-sharing.
• Right-click a virtual machine in the inventory and select Edit Settings.
  On the Virtual Hardware tab, expand SCSI controller, and select the type of sharing in the SCSI Bus Sharing to None

Additional Information

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japaneseKB:バス共有（Bus-sharing）が構成された仮想マシンでスナップショットの作成やバックアップができない