Connection to iSCSI target fails due to network failure - VMware vSphere ESXi

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

Symptoms

• The vSphere Client displays: Login to iSCSI target iqn.#### on vmhba## failed. The iSCSI initiator could not establish a network connection.
• In /var/log/vobd.log, events similar to the following appear: 
  
  [iscsiCorrelator] [vob.iscsi.target.connect.error] vmhba## @ vmk# failed to login to iqn.#### because of a network connection failure. [iscsiCorrelator] [vob.iscsi.target.async.event] The target iqn.#### issued an async event for vmhba## with reason code 0003
• Storage adapter paths show a state of "Dead" or "Offline".
• Datastores may enter "All Paths Down" (APD) state.
• VMs are in inaccessible state or stuck in boot loop.

Environment

• VMware vSphere ESXi 7.x / 8.x

 

Cause

• Improper storage array configuration, host networking mismatches, physical hardware failure (SFPs/Cabling), or MTU size inconsistencies across the fabric.

Resolution

1. Verify if the iSCSI initiator configuration is correct and ports are unbound/bound correctly.
   
   
2. Test connectivity using vmkping to the target portal: vmkping -I vmk# ###.###.###.### -d -s 1472


3. Ensure the storage device has a default gateway defined and can ping the host.
   
   
4. Verify MTU consistency (e.g., Jumbo Frames 9000) end-to-end.
   
   
5. Check physical link status on the storage array and network switch ports.
   
   
6. If reason code 0003 is present, engage the storage vendor to inspect for hardware or controller-side failures.

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Additional Information

Japanese KB: 418934