ESXi hosts goes into not responding state with "Cannot connect to storage" events

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• The ESXi host enters a "Not Responding" state in vCenter Server.

• All virtual machines residing on the affected host become unresponsive and lose network connectivity.

• The Monitor > Events tab for the host displays the following error message: "Cannot connect to storage"

   

Environment

VMware vSphere ESXi 8.x

Cause

This issue occurs when the storage adapter driver fails to successfully post I/O requests due to errors detected on the remote port. Consequently, the driver enters a continuous retry loop, repeatedly attempting to dispatch commands to the hardware. This excessive activity depletes available host resources, causing the management agents to stall and the host to enter a "Not Responding" state in vCenter.

Cause Validation:

From /var/run/log/vmkernel.log file, below events are observed:

2025-11-19T05:18:32.990Z In(182) vmkernel: cpu7:2097302)qedf:vmhba4:qedfc_command:1268:Error: unable to post io_req
2025-11-19T05:18:32.990Z In(182) vmkernel: cpu7:2097302)qedf:vmhba4:qedfc_cmd_release:577:Error: active_ios on rport 0x431xxxxxxxxxx = 0x0

Resolution

Engage the Fibre Channel switch vendor to investigate the underlying cause of the errors reported on the remote port (rport).