Unmounting a File System Using Mirrormounts

Mirrormounted file systems will be automatically unmounted if idle, after a certain period of inactivity. The period is set using the AUTOMOUNT_TIMEOUT property in /etc/default/autofs, which is used by the automounter for the same purpose.

If an NFS file system is manually unmounted, then any mirrormounted file systems contained within it will also be unmounted, if idle. If there is an active mirrormounted file system within, the manual unmount will fail, as though that original file system were busy. A forced unmount will, however, be propagated through to all enclosed mirror-mounted file systems.

If a file system boundary is encountered within an automounted file system, a mirrormount will occur. When the automounter unmounts the parent filesystem, any mirror-mounted file systems within it will also be automatically unmounted, if idle. If there is an active mirrormounted file system, the automatic unmount will not occur, which preserves current automount behavior.