Zrep is an enterprise-grade, single-program solution for handling asynchronous,
continuous replication of a zfs filesystem, to another filesystem.
That filesystem can be on another machine, or on the same machine.

It also handles 'failover', as simply as "zrep failover datapool/yourfs".
This will conveniently handle all the details of

 - Making 'yourfs' be a data destination, rather than a source
 - Making 'yourfs' be read-only
 - Making the destination fs be "live", and ready to transfer data to yourfs

WWW: http://www.bolthole.com/solaris/zrep/