ZREP is a ZFS based replication and failover script from bolthole.com
Got ZFS on two systems? Want to have (almost) idiotproof replication and master/servant switching between them? Install zrep with a single download and you're almost ready to go.
Step 1: wget https://raw.githubusercontent.com/bolthole/zrep/master/zrep (and make it executable of course. Plus copy it to your second host)
Step 2: zrep -i pool1/prodfs host2 destpool/prodfs
Step 3: (put in cron, every minute if you like) zrep -S pool1/prodfs
And you're done! At least with a super-simple implementation. Note that this is a Korn shell script, so you will need /bin/ksh on your system.
Many, many more options and features are documented, at
http://www.bolthole.com/zrep/zrep.documentation.html
Note that to enable bash commandline completion, an additional download is needed;
sudo wget -O /etc/bash_completion.d/zrep https://raw.githubusercontent.com/bolthole/zrep-completion/master/src/zrep