For Disaster Recovery solutions most of the system should be replicated directly using internal mechanisms vs. utilizing global mechanisms like VM intance mirroring. Proprietary mechanisms are less wasteful and allow smoother fail over.
We continually optimize Backup and DR technology to guarantee that our clients do not waste any capacities and resources. For example, we do not implement a repetitive backup of the entire VM snapshot, if that VM instance is a dedicated Database Server. Databases have their own highly efficient mechanisms for backup which we use to preserve transactional data integrity and to provide fast recoverability.