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

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

Symptoms:

When working with a combination of Raw Device Mapping (physical or virtual), Microsoft Clustering (MSCS), Snapshots,Consolidated Backup, and/or Data Recovery, you may experience these symptoms:

• 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, you may see an error similar to:

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 2.x}

^{VMware vSphere Esxi 3.x}

^{VMware vSphere Esxi 4.x}

^{VMware vSphere Esxi 5.x}

^{VMware vSphere Esxi 6.x}

^{VMware vSphere Esxi 7.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.}
• <sup>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 https://knowledge.broadcom.com/external/article/316575/consolidatingcommitting-snapshots-in-vmw.html</sup> 

^{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.}

Additional Information

^{https://docs.vmware.com/en/VMware-vSphere/7.0/com.vmware.vsphere.vm_admin.doc/GUID-2F4A6D8B-33FF-4C6B-9B02-C984D151F0D5.html}