Troubleshooting ESXi Fibre Channel Path Count Inconsistencies for IBM SVC VMware vSphere ESXi

Products

• VMware vSphere ESXi

Issue/Introduction

Identify and resolve scenarios where ESXi hosts report fewer Fibre Channel (FC) paths than expected when connected to IBM SVC storage. This often occurs during "Transitional Mode" migrations or firmware upgrades where physical and virtual WWPNs are co-present.

Symptoms

• Expected path count (e.g., 32) does not match observed path count (e.g., 8).
• No path errors in VMkernel logs.
• Inconsistent visibility across different LUNs or I/O Groups.

 

Environment

• VMware vSphere ESXi (all versions)
• IBM SVC Storage Arrays (Firmware 8.5+)
• Configuration: Transitional Mode (Physical and Virtual WWPNs)

Cause

The issue is generally not a failure, but an architectural design aspect of IBM SVC:

• I/O Group Scoping: LUNs presented from one I/O Group are not reachable via other I/O Groups. The host correctly reports only the paths valid for that specific LUN/Group assignment.
• Transitional Mode: Concurrent zoning of legacy physical WWPNs and new virtual WWPNs can lead to temporary path enumeration complexity during fabric changes.

Resolution

1. Run the following command to review current path state: esxcfg-mpath -b
2. Inspect the output to verify which target WWPNs are active for the LUNs in question.
3. Confirm with the storage team that the WWPNs zoned correspond to the specific I/O Group hosting the LUNs.
4. Remove legacy physical zones only after ensuring Virtual WWPNs are correctly discovered and paths are active.
5. Execute a storage rescan to trigger a refresh of the path topology: esxcli storage core adapter rescan --all
6. Monitor /var/run/log/vmkernel.log to ensure all targets are re-discovered correctly.

Additional Information

• For further guidance on FC fabric zoning best practices, refer to your IBM SVC storage array documentation.
• To speak with a customer representative or a Support Engineer see Contact Support. Scroll to the bottom of the page and click on your respective region.