High Latency Causes vCenter and VMs impossible to manage

Products

• VMware vSphere ESXi

Issue/Introduction

System-wide performance degradation is observed due to high I/O latency on multiple NFS datastores. This issue manifests as unresponsive VMs including vCenter

Environment

ESXi 7.x

ESXi 8.x

Cause

The root cause is a significant latency condition originating on the external NFS storage target or its network path. This is evidenced by repeated vmkernel log warnings indicating that the NFS volume's I/O latency has exceeded the 10000(us) threshold, causing communication failures between the ESXi hosts and the datastore.

2025-09-25T06:46:49.012Z cpu64:2098380)WARNING: NFS: 5043: NFS volume NFSDatastoreName performance has deteriorated. I/O latency increased from average value of 0(us) to 10290(us). Exceeded threshold 10000(us) 
2025-09-25T06:46:50.188Z cpu55:2098380)WARNING: NFS: 5043: NFS volume NFSDatastoreName performance has deteriorated. I/O latency increased from average value of 10290(us) to 20788(us). Exceeded threshold 10000(us) 

Resolution

To resolve this issue, the source of the high latency must be investigated outside of the ESXi hosts. Troubleshooting should focus on the network path to the NFS target and the performance of the storage array itself, as the ESXi logs confirm the issue is external to the host. See Interpreting NFS datastore's latencies related messages in vmkernel logs for more details.