The best way to ensure that a backup copy is available for restoration of mission critical data after a disaster is to periodically test backups stored in a remote location. Testing backups is essential to verify that the backup copies are valid, complete, and recoverable. Testing backups also helps to identify any issues or errors that may affect the backup process or the restoration of data. Storing backups in a remote location is important to protect the backup copies from physical damage, theft, or unauthorized access that may occur at the primary site. Using an electronic vault for incremental backups, deploying a fully automated backup maintenance system, or using both tape and disk backup systems are not sufficient to ensure that a backup copy is available for restoration of mission critical data after a disaster, as they do not address the need for testing backups or storing them in a remote location. References: Backup and Recovery of Data: The Essential Guide | Veritas, The Truth About Data Backup for Mission-Critical Environments - DATAVERSITY.