Overview
When a failure happens, it is not just data that needs restoring, but the full working environment; in other words, disaster recovery.
Backup is an aspect of disaster recovery but not the full story; backups are a component of a disaster recovery plan. The overall goal of disaster recovery is to be able to get systems restored and running as quickly as possible, including the associated data.
The increasing use of virtualization has changed the way disaster recovery is carried out because, in a virtual world, a system can be recovered by duplicating images of virtual machines (VM) and recreating them elsewhere. In a VM environment snapshots now for an integral part of any disaster recovery plan.
Part of the planning is determining your RPO tolerance (how much, if any data or recent configuration changes you are prepared to lose)
The amount of resources that one puts into the disaster recovery program will depend on your RTO. 