Can I install another Security Director server (ESXi) at one of my other data centres and configure it to act as the backup server? I do this at the moment with Checkpoint - the primary and secondary servers have a heart beat link ... if primary goes down then the secondary realises and makes itself the primary to push out firewall policies to the gateways.
In general you would only need licenses for Junos Space and Security Director on the primary/active installation. Doing the manual disaster recovery will import the licenses from the backup.
Right now I cannot find information on the full disaster recovery solution will require licenses on both sites. I will try to find out an update this thread if other people have not been able to answer before me.