Hello Steve,
Unfortunately at this time there is no supported method of fail over or Disaster Recovery for the Infrastructure Manager product suite including the Data Aggregator, Data Repository, Data Collector and CA Performance Center servers.
It is something on the mind of the Product Management team but when it will be added to a future release is unknown at this time.
For the data in the systems it is best to ensure both the Data Repository Vertica database and the netqosportal and em MySql databases are backed up successfully on a regular basis. As always be sure they are stored in a safe location. With that set aside it makes rebuilding the systems in the event of unrecoverable catastrophic failure much much easier.
Linux VM machines could also have snapshots set aside if possible for easy system resets.
Sorry for the negative answer, but hopefully that answers your questions posed here.
Thanks,
Michael