You cannot grow or shrink any volume associated with an encapsulated root disk (rootvol, usr, var, opt, swapvol, and so on) because these map to a physical underlying partition on the disk and must be contiguous. If you try to grow rootvol, usrvol, varvol, or swapvol, the system could become unbootable if you need to revert back to booting from slices. It can also prevent a successful Solaris upgrade, and you might have to do a fresh install. Theupgrade_start script might also fail.