NFS automount considerations

The default file system type when using the automounter daemon is NFS. When the -fstype option is not specified, and the server is the local node, a soft-mount of the local directory is done at the desired mount point. JFS is assumed as the only handler of local directories. A GPFS file system local soft-mount does not work implicitly, since the mount request is passed to JFS which then produces an error. When specifying -fstype mmfs the local soft-mount works because the mount is then passed to GPFS instead of JFS.

A GPFS soft-mount does not automatically unmount. Setting -fstype nfs3 causes the local server mounts to always go through NFS. This allows you to have the same auto.map file on all nodes whether the server is local or not, and the automatic unmount will occur. If you want local soft-mounts of GPFS file systems while other nodes perform NFS mounts, you should have different auto.map files on the different classes of nodes. This should improve performance on the GPFS nodes as they will not have to go through NFS.