Frequent loss of path redundancy with PDL error (0x5/0x25/0x0)

Products

• VMware vSphere ESXi

Issue/Introduction

• Frequent alerts in vSphere Client: "Path redundancy to storage device naa.############################# degraded" with respect to one or more devices
  
  

• vmkernel.log reports repeated entries similar to:
  
  Wa(180) vmkwarning: cpu##:2098914)WARNING: NMP: nmp_PathDetermineFailure:3536: Cmd (0x8a) PDL error (0x5/0x25/0x0) - path vmhba#:C#:T#:L# device naa.############################# - triggering path failover
  
  
  
• Successful failover occurs to another path to the device"
  
Wa(180) vmkwarning: cpu##:2098331)WARNING: NMP: nmpDeviceAttemptFailover:644: Retry world failover device "naa.#############################" - issuing command 0x45ba8165cb40
  
  
  
• /var/log/vobd.log reports path redundancy is restored in within a few seconds:
  
  In(14) vobd[2098150]  [scsiCorrelator] 4635641116859us: [esx.problem.storage.redundancy.degraded] Path redundancy to storage device naa.############################# degraded. Path vmhba#:C#:T#:L# is down. Affected datastores: Unknown.
In(14) vobd[2098150]  [scsiCorrelator] 4635649117414us: [esx.clear.storage.redundancy.restored] Path redundancy to storage device naa.############################# (Datastores: Unknown) restored. Path vmhba#:C#:T#:L# is active again.

Environment

VMware vSphere ESXi 7.x
VMware vSphere ESXi 8.x

Cause

The storage array is briefly and intermittently reporting devices to be permanently unavailable on specific paths, without the device entering a PDL state on all paths. As such path redundancy is temporarily degraded and path failover is triggered.  

Resolution

Engage the storage vendor to investigate the cause of the device becoming temporarily unavailable (PDL status) on specific paths

Additional Information

See: 
Permanent Device Loss (PDL) and All-Paths-Down (APD) on host
Understanding the storage path failover sequence in VMware ESXi native multipathing