Mismatch between LUN and Host ID when LUN is presented to clustered ESXi hosts from multiple storage groups

Products

• VMware vSphere ESXi

Issue/Introduction

 

Symptoms:

• vMotion fails due to LUN ID mismatch.
• Raw Device Mapping (RDM) bus sharing fails for Microsoft Clustering Services (MSCS).
• Cannot see some or all storage devices in VMware vCenter Server or Virtual Center.
• LUN in multiple Storage Groups do not have matching Host Logical Unit (HLU) entries.

Environment

 

VMware vSphere ESXi 6.x/7.x

Cause

EMC Access Logix provides storage access controls between internal Array Logical Unit (ALU) and host initiators. Access Logix internally performs ALU mapping to host initiators through using host LUN numbers (HLUs or Host IDs).

Mappings are created and managed through Storage Groups. Unless specified during Storage Group creation, the HLU is automatically allocated. The same HLU is presented to all host initiators in a group. Only the HLU is visible to the ESXi host initiator.

The issue occurs when ESXi host initiators in a vSphere Cluster are in different EMC Access Logix Storage Groups, with different automatically allocated HLUs.

Resolution

To resolve this issue, add the LUN to the correct HLU that matches.

 

To add the LUN to the correct HLU that matches the virtual Storage Group in use by the cluster:

1. Shut down servers that use the Storage Group that can be changed because removing a LUN from the group makes it unavailable.
   
   
2. If the LUN and the HLU do not match, resolve this by removing LUN from one group and then readd with a HLU that matches one in use by this cluster.
   
   Note: Ensure that the HLU is available.
   
   
3. After the changes are done to the Storage Groups, reboot the host. The LUNs should now be detected with their new HLU ID.

Additional Information

If you do not map LUNs with an identical HLU across a clustered host, you may experience issues.