You can specify more than one location in the location field of a single entry in a direct or indirect map. This means that the mounting can be done from any of the locations specified.
Specifying multiple locations makes sense when you are mounting a resource read-only but not for writable resources, since you generally want to have control over the locations of files you write or modify. An example of a read-only resource you might mount from a variety of locations is online documentation. In a large network, the current set of online manual pages may be available from more than one server. It doesn't matter which server you mount them from, as long as the server is up and running and sharing its files. For an example, see ``Example: multiple locations''.
If the server goes down while the mount is in effect, the resource becomes unavailable. You can wait five minutes until the auto-unmount takes place and try again; next time around, the automounter will choose one of the available servers. You can also use the umount command, inform the automounter of the change in the mount table, and retry the mount. (See ``Updating the mount table'' for more information.)
For example, if manual pages reside in a directory /usr/man on three different hosts, called oak, rose, and willow, you can mount from any location by specifying the following in the direct map:
/usr/man -ro,soft oak:/usr/man rose:/usr/man \ willow:/usr/manThis could also be expressed as a comma-separated list of servers, followed by a colon and the pathname (as long as the pathname is the same on all servers):
/usr/man -ro,soft oak,rose,willow:/usr/manFrom the list of servers, the automounter first selects those that are on the local network and queries or ``pings'' them. The first server to respond is selected, and an attempt is made to mount from it.