SAN physical layer connectivity issue.

Products

• VMware vSphere ESXi

Issue/Introduction

• CRC errors and fluctuating Rx/Tx values reported on port from switch level.
  

• From switch level, "porterrshow" displays increasing CRC errors (Cyclic Redundancy Check) and "sfpshow"with low Rx optical power values.
  
  porterrshow -i

           frames        enc     crc     crc     too     too     bad     enc    disc    link    loss    loss    frjt    fbsy     c3timeout     pcs      uncor
         tx       rx      in     err     g_eof   shrt    long    eof     out    c3      fail    sync    sig                      tx      rx      err     err
10:    2.7m    2.6m    0       300       3       0       0       0       0       0       0       0       0       0       0       0       0      10.1k    0

sfpshow

Slot  #/Port ##:
=============
Identifier:  3    SFP
Connector:   7    LC
[...]
Vendor Name: BROCADE
Current:     7.496   mAmps
Voltage:     3312.0  mVolts
RX Power:    -9.1    dBm (121.80uW)
TX Power:     -2.4    dBm (572.80 uW).
  
  

• From ESXi, var/run/log/vmkernel.log - (H:0x8) indicates the HBA driver has aborted I/O operations due to target resets or timeouts.
  
2025-12-15T15:52:13.292Z In(182) vmkernel: cpu45:2098278)NMP: nmp_ThrottleLogForDevice:3893: Cmd 0x2a (0x45b9ef46f1c0, 2101229) to dev "naa.########################" on path "vmhbaX:C0:T1:L1" Failed:
2025-12-15T15:52:13.292Z In(182) vmkernel: cpu45:2098278)NMP: nmp_ThrottleLogForDevice:3898: H:0x8 D:0x0 P:0x0 Act:EVAL. cmdId.initiator=0x430d1fe19c40 CmdSN 0xffffd08ce5349030
2025-12-15T15:52:13.292Z Wa(180) vmkwarning: cpu45:2098278)WARNING: NMP: nmp_DeviceRequestFastDeviceProbe:235: NMP device "naa.########################" state in doubt; requested fast path state update...
  

Environment

VMware ESXi 8.x
Brocade Fibre Channel Switch.

Cause

The issue is caused from a physical layer failure, where signal degradation at the SAN switch port is resulting in frame corruption and CRC errors.

Resolution

Engage the Switch vendor to perform a validation on the physical layer and address the connectivity issues.