Best Backup Strategy for Mission-Critical Applications with Low RTO

B.

For mission-critical applications with a low recovery time objective (RTO), the best backup strategy would be "mirroring" (Option B).

Mirroring involves replicating data in real-time from a primary storage location to a secondary one. This creates an exact copy of the data, which can be accessed immediately if the primary system fails. Mirroring is also known as RAID 1 (redundant array of independent disks) and is a common technique used in high-availability environments.

Option A, frequent backups to tape, is not the best backup strategy for mission-critical applications with a low RTO because it can take a long time to restore data from tape. Also, frequent backups can cause performance issues and consume a lot of storage space.

Option C, using virtual tape libraries, can be a good backup strategy as it provides faster backup and recovery times than tape-based backups. However, it may not be the best option for mission-critical applications with a low RTO as it still involves restoring data from a backup.

Option D, archiving to conventional disk, is not the best backup strategy for mission-critical applications with a low RTO as it can take a long time to restore data from an archive.

In summary, the best backup strategy for mission-critical applications with a low RTO is mirroring, as it provides real-time replication and immediate access to the data in case of a primary system failure.