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

Symptoms

When working with a combination of Raw Device Mapping (physical or virtual), Microsoft Clustering, 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.

Resolution

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 Clusters Nodes that exist across different physical hardware require virtual controllers to be in bus sharing configuration.
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.

For more information, see the following references:

VMware Consolidated Backup Limitations in the Virtual Machine Backup Guide.
Limitations of Raw Device Mapping in the ESX Configuration Guide.

Workaround

If you require bus-sharing, do the following:

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. For more information, see the Using Snapshots section of the vSphere Basic Administration Guide for your version of VMware ESX.
Note: If snapshot consolidation fails, see Consolidating Snapshots (1007849).

If you do not require bus-sharing, do the following:

If your virtual machine is currently configured with bus-sharing, but you wish to create snapshot, you must disable bus-sharing. For more information, see the Managing Mapped LUNs section of the ESX Configuration Guide for your version of VMware ESX.

This Article Replaces

1014311, 1004972, 1013158, 1021679

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