To resolve this issue, validate that these steps are true for your VMware environment:
Caution: Do not skip a step. The steps provide instructions or a link to a document for validating the step and taking corrective action as necessary. The steps are ordered in the most appropriate sequence to isolate the issue and identify the proper resolution.
Check the MTU size configuration on the port group which is designated as the NFS VMkernel port group. If it is set to anything other than 1500 or 9000, test the connectivity using the vmkping command:
# vmkping -I vmkN -s nnnnxxx.xxx.xxx.xxx
Where:
vmkN is vmk0, vmk1, etc, depending on which vmknic is assigned to NFS. nnnn is the MTU size minus 28 bytes for overhead. For example, for an MTU size of 9000, use 8972.
xxx.xxx.xxx.xxx is the IP address of the target NFS storage.
To reveal the vmknics, run the command:
esxcfg-vmknic -l
Check the output for the vmk_ interface associated with NFS.
Verify that the NFS host can ping the VMkernel IP of the ESXi host.
Verify that the virtual switch being used for storage is configured correctly.
Note: Ensure that there are enough available ports on the virtual switch.
Verify that the storage array is listed in the VMware Hardware Compatibility Guide. For more information, see the VMware Compatibility Guide. Consult your hardware vendor to ensure that the array is configured properly.
Note: Some array vendors have a minimum microcode/firmware version that is required to work with the ESXi host.
Verify that the physical hardware functions correctly. Consult your hardware vendor for more details.
If the above troubleshooting has not resolved the issue and there are still locked files, e.g. attempting to unmount the NAS volume may fail with an error similar to:
WARNING: NFS: 1797: <NFS UUID> has open files, cannot be unmounted