The common interpretation of DR on i5 is a failover to another i5 in the event the production system crashes.
A HA software can achieve this the quickest since your data is mirrored to the failover i5.
Sunguard is used but is slower and far more expensive.
As mentioned it depends on your company’s business requirements as to which of the several options you use.
How do you mean? DR can be whatever it needs to be in your business environment.