Mount command fails against Cluset IP / Name

I came across a scenario where mount command was failing when we put it across the Cluster IP / Cluster Name that the Windows NFS share was part of. The same command worked perfectly against the actual IP / Name of the Windows NFS share (active Node).

A closer look at the network trace showed that the mount call getting no access and the reply was from the actual IP whereas the mount request was going to the Cluster (virtual) IP.

We have found that if TCP is used as the protocol the mount command works properly against the virtual IP / Name. Additionally, “-c” command in the mount command can be used to make use of UDP protocol at the same time ensuring a successful mount command against virtual IP / Name.

Some *nix clients have a specific option for this. From freebsd mount_nfs man page. -c For UDP mount points, do not do a connect(2). This must be used if the server does not reply to requests from the standard NFS port number 2049 or replies to requests using a different IP address (which can occur if the server is multi-homed). Setting the vfs.nfs.nfs_ip_paranoia sysctl to 0 will make this option the default.