Solaris Live Upgrade copies the entire contents of a slice to the designated new boot environment slice. You might want some large file systems on that slice to be shared between boot environments rather than copied to conserve space and copying time. File systems that are critical to the operating environment such as root (/) and /var must be copied. File systems such as /home are not critical file systems and could be shared between boot environments. Shareable file systems must be user-defined file systems and on separate swap slices on both the active and new boot environments. You can reconfigure the disk several ways, depending your needs.
You can reslice the disk before creating the new boot environment and put the shareable file system on its own slice. For example, if root (/), /var, and /home are on the same slice, reconfigure the disk and put /home on its own slice. When you create any new boot environments, /home is shared with the new boot environment by default.
If you want to share a directory, the directory must be split off to its own slice. The directory is then a file system that can be shared with another boot environment. You can use the lucreate command with the -m option to create a new boot environment and split a directory off to its own slice. But, the new file system cannot yet be shared with the original boot environment. You need to run the lucreate command with the -m option again to create another boot environment. The two new boot environments can then share the directory.
For example, if you wanted to upgrade from the Solaris 8 release to the Solaris 9 release and share /home, you could run the lucreate command with the -m option. You could create a Solaris 8 release with /home as a separate file system on its own slice. Then run the lucreate command with the -m option again to duplicate that boot environment. This third boot environment can then be upgraded to the Solaris 9 release. /home is shared between the Solaris 8 and Solaris 9 releases.
For a description of shareable and critical file systems, see Creating a Boot Environment Overview.