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Managing Network File Systems in Oracle® Solaris 11.4

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Updated: August 2021

How Mirror Mounts Work

The Oracle Solaris 11 release includes a new mounting facility called mirror mounts. Mirror mounts allow an NFS Version 4 client to access files in a file system as soon as the file system is shared on an NFS Version 4 server. The files can be accessed without the overhead of using the mount command or updating autofs maps. In effect, after an NFS Version 4 file system is mounted on a client, any other file systems from that server can also be mounted.

    Generally, using the mirror mounts facility is optimal for your NFS Version 4 clients except when you need to do the following:

  • Use a different hierarchy on the client than exists on the server

  • Use different mount options than those of the parent file system

Mounting a File System Using Mirror Mounts

If a file system is mounted on an NFS Version 4 client by using manual mounts or autofs, any additional file systems that are added to the mounted file system can be mounted on the client by using the mirror mount facility. The client requests access to the new file system with the same mount options that were used on the parent directory. If the mount fails for any reason, the normal NFS Version 4 security negotiations occur between the server and the client to adjust the mount options so that the mount request succeeds.

When an automount trigger exists for a particular server file system, the automount trigger takes precedence over mirror mounting, so a mirror mount will not occur for that file system. To use mirror mounts in this case, the automount entry must be removed.

In the Oracle Solaris 11 release, accessing the /net or /home automount point causes a mount of the /net or /home server namespace. Access to directories or files under those directories is given through the mirror mounts facility.

For specific instructions about how to use mirror mounts, see How to Mount All File Systems From a Server.

Unmounting a File System Using Mirror Mounts

Mirror-mounted file systems are automatically unmounted if they are idle after a certain period of inactivity. The period is set by using the timeout parameter, which is used by the automounter for the same purpose.

If an NFS file system is manually unmounted, then any mirror-mounted file systems contained within it are also unmounted, if idle. If a mirror-mounted file system is active, the manual unmount fails as though that original file system were busy. However, a forced unmount is propagated through all the contained mirror-mounted file systems.

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