vMotion Fails with SCSI Controller Engaged in Bus-Sharing Error Due to conflict with Multi-Writer.

Products

• VMware vSphere ESXi
• VMware vSphere ESXi 8.0

Issue/Introduction

When attempting to perform a hot migration (vMotion) of a Virtual Machine (VM), the operation fails with the following error message:

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

Other VMs in the same environment or cluster may migrate without issues, even if they appear to have similar configurations.

Environment

VMware vSphere ESXi 8.x

VMware vSphere ESXi 9.x

Cause

This issue occurs because the VM is configured with a conflicting disk-sharing setup on the same SCSI controller. Specifically, the VM has both Physical SCSI Bus Sharing enabled at the controller level and the Multi-writer flag enabled at the virtual disk level.

VMware vSphere does not support the simultaneous use of Physical Bus Sharing and the Multi-writer flag on the same controller for hot migrations. These two features provide different methods of shared access and are mutually exclusive for vMotion operations.

Resolution

To resolve this issue and enable vMotion, you must align the VM configuration with a supported sharing model. The correct configuration depends on your specific clustering requirements (e.g., Oracle RAC, Microsoft WSFC).

Note: Changing disk sharing modes or controller settings requires a VM power-off. Consult your guest operating system or clustering software vendor (e.g., RAC or Microsoft) before making these changes to ensure the cluster heartbeating and data integrity mechanisms remain functional.

Step 1: Identify the Conflicting Configuration

1. Right-click the affected VM in the vSphere Client and select Edit Settings.
2. Locate the SCSI controller identified in the error message (e.g., SCSI controller 1).
3. Check the SCSI Bus Sharing field. Note if it is set to Physical.
4. Expand the Hard disk entries attached to that controller and check under Sharing. Note if it is set to Multi-writer.

Step 2: Apply a Supported Configuration

Choose one of the following options based on your application's documentation:

Option A: Use Multi-writer (Recommended for Oracle RAC and specific Linux clusters)

If your application requires the Multi-writer flag:

1. Power off the VM.
2. Change SCSI Bus Sharing on the controller to None.
3. Ensure the disks remain set to Multi-writer.
4. Power on the VM and attempt the vMotion.

VMware Oracle Hybrid Cloud High Availability Guide

Enabling or disabling simultaneous write protection provided by VMFS using the multi-writer flag

Option B: Use Physical Bus Sharing (Common for WSFC configurations)

If your application strictly requires Physical Bus Sharing:

1. Power off the VM.
2. Keep SCSI Bus Sharing set to Physical.
3. Change the Sharing mode on the virtual disks to No sharing.
4. Power on the VM and attempt the vMotion.

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

Microsoft Windows Server Failover Clustering (WSFC) with shared disks on VMware vSphere 9.x: Guidelines for supported configurations

 

Additional Information

If using Red Hat Clustering please see the below:
RHEL High Availability Cluster on VMware vSphere 7.x, 8.x & VMware Cloud Foundation 9.0: Guidelines for supported configurations