Automounting

A new version of the automounter, called AutoFS, has been included. In the SunOS release 4 releases, the automounter mounted everything under /tmp_mnt and used symbolic links to redirect the lookups. AutoFS allows for file systems to be mounted in place (for instance, /home).

In SunOS release 4, the maps for the automounter were named auto.master and auto.home. For Solaris 7, these maps have been renamed to auto_master, auto_home, and so on. The NIS+ name service, which is included with the release, requires this change. A default copy of these maps is included in the release, so that the AutoFS service is started when the system is booted. The SunOS release 4 releases did not include the maps, so additional installation steps were required.

The Solaris 7 release provides the ability to select the name service that is being used through /etc/nsswitch.conf. The automount entry can be changed to select local files, NIS+, NIS, or some combination of these.

Earlier releases supported a home directory naming convention like: /home/server/login. With the AutoFS maps it is much easier to use /home/login for each entry. This new naming convention also provides for location independence. The old convention can still be used, but once a transition to using the AutoFS maps has been made, it will be easier to administer the shorter paths.

The following paths were reserved for use by AutoFS:

• /net - for mounting file systems from a known host

• /home - for mounting the home directory of a known user

• /xfn - for mounting file systems that support the X/Open XFN standard

On home directory servers, the actual home directories should be moved to /export/home rather than /home, so that they do not conflict with the automounter directory structure. This also means that you cannot mount file systems on /home while the automounter is running.

The AutoFS software now has two programs. The first program is automount that runs at boot time to establish AutoFS mount points. This command can also be run anytime by superuser to change the mount points. The second command is automountd, which is a stateless daemon that answers AutoFS file system mount and unmount requests. These two programs replace the SunOS release 4 automount daemon.

The automount daemon is now fully multi-threaded. Multiple automatic mount requests can be serviced concurrently, which makes AutoFS more reliable. In short, one mount request could block connecting to a slow server, while a second request is processed without waiting.

The Solaris 7 release supports browsability of indirect AutoFS maps. All mountable entries under an AutoFS mount point (for example, /home) are now visible without the overhead of mounting them first.

Also provided is improved on-demand automounting of hierarchically related file systems. Previous releases would automount an entire set of file systems if they were hierarchically related (for example, /net/server) even if only one of the file systems was referenced. The file system that is referenced is dynamically mounted without mounting all of the other file systems in the hierarchy. Other file systems are mounted when they are individually referenced.

See "Mounting File Systems and autofs" for more detailed information. Also, NFS Administration Guide describes how to use AutoFS.