To access z/OS UNIX files or z/OS conventional MVS data sets, enter both the mvslogin command to log in to the z/OS host system and the mount command to mount the files or data sets to your local system. The mvslogin command is only required when accessing data on systems where the z/OS NFS server site security attribute is set to saf or safexp. Once the files or data sets are mounted to a local directory, you can read, write, create, delete, and treat the mounted files as part of your workstation's local file system. When you are finished with your work, use the umount and mvslogout commands to break the connection. The mvslogout command is only required when the mvslogin command was used to begin the connection.

z/OS UNIX file systems and MVS data sets are very different and require different management techniques. Prior to z/OS V1R11, the NFS server distinguished between the two by the fact that z/OS UNIX file system paths are prefixed with an hfs prefix value (/hfs/pathname) and MVS data sets are not, The hfs prefix is not actually part of the path name. It is only intended as a trigger to tell the z/OS NFS Server that the specified path is a z/OS UNIX path, not an MVS data set. Based on the presence, or absence, of a prefix, the NFS Server invokes its appropriate data management functions.

Starting in V1R11, the z/OS NFS file system type management function has been expanded by adding an mvs prefix and a customer-configurable path resolution heuristic. The new mvs prefix provides the capability for the customer to explicitly specify a prefix for identifying MVS data sets, like the hfs prefix does for z/OS Unix files. The customer-configurable heuristic allows the customer to specify how to interpret absolute path names that do not have a prefix specified.