Frequent 'PowerOn Reset Unit Attention' Alerts on ESXi Hosts Indicating Potential SAN Connectivity or Stability Issues

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

• Event messages like "Frequent PowerOn Reset Unit Attentions are occurring on device naa.60034987. This may indicate a storage problem. Affected datastores: vmdatafiles"
• Entries in the vobd.log file (located at /var/log/) resembling: [

scsiCorrelator] 50622937505us: [vob.scsi.scsipath.por] Power-on Reset occurred on vmhba37:C0:T1:L200

• SAN Congestion: The SAN might experience severe congestion, leading to prolonged I/O request completion times.
• Degraded Storage Performance: The performance of virtual machines (VMs) relying on the affected datastores can be significantly impacted.

Resolution

Investigate the SAN:

• Consult with your SAN vendor or administrator to diagnose and address the root cause of the frequent PowerOn Reset Unit Attentions.

Monitor Performance

• Closely monitor the performance of the affected datastores and VMs for any signs of degradation.

Consider Alternatives:

• If the issue persists, consider migrating VMs to alternative datastores or hosts to minimize performance impact.

Note: This issue is likely caused by a hardware or configuration problem within the SAN. Addressing the underlying issue is crucial to ensure the stability and performance of your virtualized environment.