If you use Oracle Solaris, then compare https://community.oracle.com/docs/DOC-912067
If you use OmniOS/OI, compare http://constantin.glez.de/blog/2011/03/how-set-zfs-root-pool-mirror-oracle-solaris-11-express
If you use OmniOS/OI, compare http://constantin.glez.de/blog/2011/03/how-set-zfs-root-pool-mirror-oracle-solaris-11-express