VMWare/ESX can’t write to a Celerra Read/Write NFS mounted datastore

I had just created serveral new Celerra NFS mounted datastores for our ESX administrator.  When he tried to create new VM hosts using the new datastores, he would get this error:   Call “FileManager.MakeDirectory” for object “FileManager” on vCenter Server “servername.company.com” failed.

Searching for that error message on powerlink, the VMWare forums, and general google searches didn’t bring back any easy answers or solutions.  It looked like ESX was unable to write to the NFS mount for some reason, even though it was mounted as Read/Write.  I also had the ESX hosts added to the R/W access permissions for the NFS export.

After much digging and experimentation, I did resolve the problem.  Here’s what you have to check:

1. The VMKernel IP must be in the root hosts permissions on the NFS export.   I put in the IP of the ESX server along with the VMKernel IP.

2. The NFS export must be mounted with the no_root_squash option.  By default, the root user with UID 0 is not given access to an NFS volume, mounting the export with no_root_squash allows the root user access.  The VMkernal must be able to access the NFS volume with UID 0.

I first set up the exports and permissions settings in the GUI, then went to the CLI to add the mount options.
command:  server_mount server_2 -option rw,uncached,sync,no_root_squash <sharename> /<sharename>

3. From within the ESX Console/Virtual Center, the Firewall settings should be updated to add the NFS Client.   Go to ‘Configuration’ | ‘Security Profile’ | ‘Properties’ | Click the NFS Client checkbox.

4. One other important item to note when adding NFS mounted datastores is the default limit of 8 in ESX.  You can increase the limit by going to ‘Configuration’ | ‘Advanced Settings’ | ‘NFS’ in the left column | Scroll to ‘NFS.MaxVolumes’ on the left, increase the number up to 64.  If you try to add a new datastore above the NFS.MaxVolumes limit, you will get the same error in red at the top of this post.

That’s it.  Adding the VMKernel IP to the root permissions, mounting with no_root_squash, and adding the NFS Client to ESX resolved the problem.

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