Traditionally, many businesses have at some point done backup directly to relatively inexpensive tape systems. For many computer applications, it's important to have data immediately ready to be restored from a secondary disk if and when the data on the primary disk becomes inaccessible. The time to restore data from tape would be considered unacceptable. On the other hand, tape is a more economical alternative for long-term storage (archiving). Because it's also more portable, tape is often used for off-site backup and restoration in case of a disaster.



Disk-to-Disk-to Tape which is also known as D2D2T, refers to backing up data on disks first and tape (or optical disk) second. Backing up onto tape is performed at less frequent intervals than from disk-to-disk.

As backup and recovery becomes more of a chief concern in the data centers, many storage managers are looking to new technologies to make the process easier. In the near future tape is not going away, but it will be increasingly joined by disk as a core backup technology.

Tape was the only acceptable method of backup for some time. As with any other technology there have been problems, whether it be the media, the drive/library or the backup window. However, backup to disk locally, replicates the backup to offsite disk, then backup to tape there. One will never have to touch the tapes as they're offsite already. In order for this to work though, you have to have something that changes the way backups are done. It simply cannot be completed with traditional backup software because there would not be enough bandwidth to replicate full and incremental backups.

When it comes to disk-to-disk tape, there are numerous manufacturers of hardware and software that will copy the data across. Most recently introduced is the Assureon, which is a combined hardware/software platform that provides fixed-content archive storage capabilities for the enterprise. This platform is disk-based, and offers both WORM storage capabilities as well as automated retention periods in which files cannot be changed or erased until their designated retention period has elapsed.

There are those skeptics that feel that disk is not ready for "prime time." Many others may disagree. SATA Disk based arrays have penetrated every market, there are millions of these drives "spinning" and drive failures are rather infrequent. With RAID5 or RAID6 and hot spare implemented the odds of data being lost is extremely slim.