iSCSI network paths drop during leaf switch maintenance and do not recover.

Products

• VMware vSphere ESXi
• VMware vSphere ESXi 8.0

Issue/Introduction

During a planned reboot of a leaf switch, iSCSI connectivity is lost as expected. However, after the switch completes the reboot:

• The physical NIC (vmnic) link status on the ESXi host remains "Down."
  
  
• iSCSI sessions and paths do not automatically re-establish.
  
  
• All storage paths for affected LUNs show as "dead" in path management.

Environment

VMware vSphere ESXi 8.0

Cause

After the switch reboot the link state does not recover and therefore the iSCSI sessions and paths can not be re-established. 

Resolution

• While toggling the NIC state serves as a temporary workaround, a full investigation of the external physical network and leaf switch configuration should be conducted to ensure link states properly re-establish following future switch reboots.
  
  
• If a host is currently experiencing a link-down state after a switch reboot, manually toggle the administrative state of the NIC to force a renegotiation:

1. 1. Access the ESXi shell or SSH.
      
      
   2. Identify the affected NIC status:
      esxcli network nic list
      
      
   3. Set the NIC state to down and then up:
      esxcli network nic set -n vmnic<#> -a down
esxcli network nic set -n vmnic<#> -a up
Setting the admin state up or down for a vmnic interface on ESXi
      
      
   4. Confirm that the network driver and firmware is supported as per the HCL:
      Determining Network/Storage firmware and driver version in ESXi
      Broadcom | VMware | Hardware Compatibility Guide