Firewall for NFS Client Outgoing is missing

Products

• VMware vSphere ESXi

Issue/Introduction

• When trying to vMotion we see error similar to - 

  • Unable to access file [datastore_name]vm_name/vm_name.vmx
    Virtual disk 'Hard Disk 1' is not accessible on the Host: Unable to access file[datastore_name]vm_name/vm_name.vmdk
    

• When looking at the vmkernel log we see error messages similar to -

  • 2026-01-04T19:54:30.976Z In(182) vmkernel: cpu49:9532792)NFSLock: 5141: failed to get lock on file serviceId.dat.lck(.lck-d403a75d00000000) ################ on <nfs_datastore_name> ##.##.##.### (##.##.##.###): Failure. fromunlink N

Cause

NFS needs the DNS lookup to be successful in order to resolve the FQDN to an IP. Since DNS lookup is failing, the NFS re-mounts are failing after a reboot.

Resolution

Here is a workaround to restore the nfs volumes where DNS resolution has failed during NFS mount during boot.

We can run "esxcfg-nas -r" after ensuring that the DNS list has a reachable DNS server IP.

 

To list the DNS servers:

esxcli network ip dns server list

 

To add new IP to DNS:

esxcli network ip dns server add --server=<IP>

 

To restore nfs volumes:

esxcfg-nas -r