Solaris ZFS Administration Guide

The canmount Property

If this property is set to off, the file system cannot be mounted by using the zfs mount or zfs mount -a commands. Setting this property is similar to setting the mountpoint property to none, except that the dataset still has a normal mountpoint property that can be inherited. For example, you can set this property to off, establish inheritable properties for descendent file systems, but the file system itself is never mounted nor is it accessible to users. In this case, the parent file system with this property set to off is serving as a container so that you can set attributes on the container, but the container itself is never accessible.

In the following example, userpool is created and the canmount property is set to off. Mount points for descendent user file systems are set to one common mount point, /export/home. Properties that are set on the parent file system are inherited by descendent file systems, but the parent file system itself is never mounted.

# zpool create userpool mirror c0t5d0 c1t6d0
# zfs set canmount=off userpool
# zfs set mountpoint=/export/home userpool
# zfs set compression=on userpool
# zfs create userpool/user1
# zfs create userpool/user2
# zfs mount
userpool/user1                  /export/home/user1
userpool/user2                  /export/home/user2

Setting the canmount property to noauto means that the dataset can only be mounted explicitly, not automatically. This setting is used by the Solaris upgrade software so that only those datasets belonging to the active boot environment (BE) are mounted at boot time.