Replicated File Systems

Multiple location fields can be specified for replicated NFS file systems, in which case automount and the kernel each tries to use that information to increase availability. If the read-only flag is set in the map entry, automount mounts a list of locations that the kernel may use, sorted by several criteria. If a server does not respond, the kernel switches to an alternative server. Sort ordering is used by automount to determine how the next server is chosen. If the read-only flag is not set, automount mounts the best single location, chosen by the same sort ordering, and new servers are chosen only when an unmount has been possible and a remount is done. Servers on the same local subnet are given first preference, and servers on the local net are given second preference. Among servers equally far away, response times determine the order (if no weighting factors are used).

If the list includes server locations using both Versions 2 and 3 of the NFS protocol, automount chooses only a subset of the server locations on the list to ensure all entries are the same protocol level. It gives preference to Version 3 servers and uses Version 2 servers if Version 3 servers are unavailable.

If each location in the list shares the same path name, a single location can be used with a list of host names, separated by commas.

hostname,hostname...:pathname