You have a backup
somepool/iocage/...
with a dozen or so sub-datasets that contain all your jails. It's read-only, so you cannot run the jails.
In case your primary machine goes up in smoke you
- set the
somepool/iocage
dataset on the backup machine to read-write
- use
iocage activate somepool
to tell iocage that this is now the active running jail dataset
- use the UI or
iocage list
, iocage start
, ... to start your jails on the backup system
iocage activate
tells the system that this is now where your live jails reside. You cannot backup to this dataset anymore, because you cannot backup/replicate to live running jails. You only do this in case of an emergency to make the backup jails "runnable".
Afterwards you need to repair your failed system and then either create a replication in the other direction, essentially switching the roles of active and backup - or restore the jails manually via the command line.