Possible repost:ufs to zfs with zones confusion.
I want to move to zfs from a ufs configuration; zones are mounted on /zones and each zone is in a separate shared (i.e in /etc/vfstab) filesystem;
/zones/dev01; /zones/dev02 etc...
Solaris 10 10/08 Installation Guide: Solaris Live Upgrade and Upgrade Planning indicates
On a system with a UFS root (/) file system and non-global zones installed, the non-global zones are migrated if the zone is in a critical file system as part of the UFS to ZFS migration. Or, the zone is cloned when you upgrade within the same ZFS pool. If a non-global zone exists in a shared UFS (