Troubleshoot ESXi hosts that cannot connect to an NFS datastore by checking VMkernel routing, VLANs, MTU, NFS exports and network access.
Start with Check the VMkernel path and work through the six diagnostic checks in order.
Record results before changing configuration and validate the original symptom after each controlled change.
Quick checks
Start with the basic checks in this runbook before moving to deeper troubleshooting.
- Confirm the affected service or component is available.
- Check recent configuration or connectivity changes.
- Run the relevant commands and compare the result with the expected state.
Check the VMkernel path
Identify the VMkernel interface intended for NFS traffic and verify its IP, VLAN and routing configuration.
Test NFS server reachability
Test reachability to the NFS server from the correct VMkernel interface.
Check VLAN configuration
Confirm the VMkernel VLAN matches the upstream physical switch configuration.
Check MTU
If jumbo frames are used, validate the MTU across the complete path rather than on ESXi alone.
Check NFS export access
Confirm the NFS server export policy allows the ESXi host and required protocol version.
Mount and verify
Retry the datastore mount and verify stable visibility and I/O from the ESXi host.
Useful commands
Run these checks from an appropriate administrative session and replace example values with your environment.
VMkernel interfaces
esxcli network ip interface listNFS reachability
vmkping -I vmkX <nfs-server-ip>Quick troubleshooting path
Use this sequence to isolate the failing dependency before changing production configuration.
- Check the VMkernel path → Identify the VMkernel interface intended for NFS traffic and verify its IP, VLAN and routing configuration.
- Test NFS server reachability → Test reachability to the NFS server from the correct VMkernel interface.
- Check VLAN configuration → Confirm the VMkernel VLAN matches the upstream physical switch configuration.
- Check MTU → If jumbo frames are used, validate the MTU across the complete path rather than on ESXi alone.
- Check NFS export access → Confirm the NFS server export policy allows the ESXi host and required protocol version.
- Mount and verify → Retry the datastore mount and verify stable visibility and I/O from the ESXi host.
What good troubleshooting looks like
Good infrastructure troubleshooting is evidence-driven. Capture the original state, test the dependency that can prove or disprove your hypothesis, make the smallest safe change and repeat the original test.
Symptom → hypothesis → direct test → result → controlled change → validation → documentation