Fiber Channel adapters (vmhba) offline following fabric switch rebalancing.

Products

• VMware vSphere ESXi

Issue/Introduction

Following a Fabric switch rebalancing or maintenance task, multiple ESXi hosts within a cluster report offline Fibre Channel adapters (vmhbas). This results in production VM disruption, where VMs become inaccessible or stuck on boot due to storage path loss.

Symptoms:

• Fibre Channel adapters (vmhba) show as Offline in vCenter UI (Host > Configure > Storage adapter).
• Production VMs may show inaccessible, powered off, or stuck during the boot process.
• vobd.log may show All Paths Down (APD) events: Device or resource busy. Path down >140s.

          From /var/run/log/vobd.log:

     2026-07-15T03:31:11.910Z In(14) vobd[20##]:[APDCorrelator]:[vob.storage.apd.timeout]Device or filesystem with identifier [naa.600507##############] has entered the All Paths Down Timeout state after being in the All Paths Down state for 140 seconds. I/Os will now be fast failed.

• Partial redundancy loss where some hosts retain one online path while others lose all connectivity.

Environment

VMware vSphere ESXi 8.x

Cause

Fabric rebalancing tasks can cause a temporary loss of path redundancy. If a device only has paths through the affected fabric segment, an APD state is triggered. ESXi enters APD when all paths to a storage device become unavailable; if residual references remain in the management stack after physical connectivity is restored, the host may fail to reclaim the paths automatically.

Validation:

From vCenter UI> Host > Configure > Storage Adapters

 

Resolution

To restore service and clear the APD state, follow these steps:

1. Restore VM Accessibility:
   • Unregister the inaccessible VMs from the impacted hosts.
   • Re-register the VMs on hosts where vmhba adapters are confirmed Online and paths are healthy.
     
     
2. Trigger Storage Rescan:
   • Once the fabric/switch team confirms physical stability, perform a rescan of the storage adapters on the affected ESXi hosts.
     
     
3. Clear Stale APD References:
   • If a rescan fails to bring paths online, a reboot of the affected ESXi host is required to cleanly clear the storage stack.
     
     
4. Hardware Investigation:
   • Engage the storage or switch vendor to investigate why the adapters failed to automatically recover following the fabric task.

Additional Information

Review fabric redundancy configurations to ensure hosts have paths distributed across multiple independent fabric segments.

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