Error: "esx.problem.hardware.fpin.fc.congestion.oversubscription" on some hosts within a vSphere cluster.

Products

• VMware vSphere ESXi
• VMware vSphere ESXi 8.0

Issue/Introduction

Symptoms:

• vCenter reports messages similar to the following in the host/clusters events log (From Host/Cluster Inventory view, Choose Host or Cluster -> Monitor -> Events): 
  
  

Description	Type	Date Time	Task	Target	User	Event Type ID
FPIN FC oversubscription congestion: Host WWPN XXXXXXXXXXXXXXXX, target WWPN YYYYYYYYYYYYYYYY.	Warning	11/06/2025, 1:25:09 PM		testhost01.testlab.local		esx.problem.hardware.fpin.fc.congestion.oversubscription

 

• The vobd.log on the affected ESXi host reports similar messages: 

 

2025-11-06T16:40:59.836Z In(14) vobd[2097956]:  [HardwareCorrelator] 4976471995477us: [vob.hardware.fpin.fc.congestion.oversubscription] FPIN FC oversubscription congestion: Host WWPN XXXXXXXXXXXXXXXX, target WWPN YYYYYYYYYYYYYYYY

2025-11-06T16:40:59.836Z In(14) vobd[2097956]:  [HardwareCorrelator] 4976524033798us: [esx.problem.hardware.fpin.fc.congestion.oversubscription] FPIN FC oversubscription congestion: Host WWPN XXXXXXXXXXXXXXXX, target WWPN YYYYYYYYYYYYYYYY.

• You are using VMFS datastores backed by fiber channel-based SAN LUNs. 

Environment

• VMware ESXi 8.x

Cause

• The fabric ports related to the impacted hosts are overutilized. See related KB:  Congestion Oversubscription and Credit Stall events reported in /var/log/vmkernel.log on ESXi Server as well as vCenter Server

 

Verification:

• Please work with your SAN team or fabric switch vendor to investigate the port utilization of the fabric switch ports related to the hosts in the affected cluster.

Resolution

• If only a small number of hosts in the cluster are affected, then, in the short term, you can try to re-distribute the VM's across the ESXi hosts in the cluster to balance the I/O across the fabric ports more evenly, possibly adding or removing DRS rules to pin or unpin VM's to/from certain hosts, as needed to keep the storage I/O load distributed. For more information regarding add/removing DRS rules, see TechDocs: Use DRS Clusters to Manage Resources with vSphere
  
  
• When possible, try to use a Round-Robin Path Selection Policy to help distribute the load across the available HBA ports on the hosts. See KB: VMware Multipathing policies in ESXi/ESX
  
  
• If all of the hosts/fabric switch ports are affected (implying all ports are being overwhelmed), then you will need to consider adding additional HBA's and/or ESXi hosts to the cluster to help distribute the storage I/O across more fabric ports or possibly upgrading to faster switches, if possible.
  
  
• In any case, you should consult with your SAN, fabric switch vendor, and Broadcom support for recommendations for your specific environment to ensure the hardware is sized and balanced appropriately.

Additional Information

• vCenter/ESXi has a few tools to monitor VM performance to determine high I/O VM's:
  
  
• • You can monitor the VM performance in the vCenter Performance Charts. For more information on using the performance charts, see: 
    • TechDocs:
      • View Performance Charts
      • Read IOPs per Virtual Machine Disk and Write IOPs Per Virtual Machine Disk
        
        
  • You can also monitor VM performance using the ESXi tool, esxtop. For more information on using esxtop, see:
    • TechDocs: Using esxtop or resxtop in Interactive Mode
    • KB: Using esxtop to identify storage performance issues for ESXi

• • You can use also use VMware Aria Operations to monitor VM performance, as well.  See TechDocs: VMware Aria Operations