AutoFS - An Automounting File System for FreeBSD 6.x

File systems store, organize, and retrieve data for users and often these files are stored on remote machines, or removable media. The UNIX system requires that these file systems must be mounted before files can be accessed. In network environments, mounted file systems can result in extra traffic, even when the file system is mounted, but no files are used. This extra traffic is undesirable, and adversely affects the available network bandwidth, and mounted file systems require more in-kernel memory and datastructures to maintain them as ”active.” Nobody wants to keep remote file systems mounted, when they’re not in use. AutoFS works with AMD, a daemon which auto-mounts file systems, to provide an on-demand mounting facility. The purpose of AutoFS is to limit the load upon AMD, and to provide a layer of kernel control over mounting. This control is used to minimise the number of calls to the Automounting daemon (AMD) thereby providing better performance as a user navigates the ”unified” file system tree. This paper describes the implementation details of AutoFS for FreeBSD 6.x