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Tape and recovery are synonymous. But it's the automation that libraries add to the base technology that make tape a viable road forward for storage managers.
The comparative low cost for backup and recovery ensures tape's continued use to keep up with the explosion of data. New tape technologies need to maintain pace with the increasing time and cost of backup/recovery. Even though redundant and/or remote disk mirroring has become less expensive, and thus more popular, due to its higher speed, tape is still the best solution for many businesses.
Best practices for recovery take a data snapshot from disk and write it to removable tape cartridges. Then the cartridges are sent to a safe, off-site archive. Tape overcomes single points of disk failure like software corruption cascading to the mirror or disasters, including sabotage, affecting both locations. For example, several companies mirrored from one World Trade Center tower to the other before Sept. 11. Others mirrored from their WTC tower to buildings across the street, which were also destroyed.
When using tape, a library is the most efficient method for fast, reliable backup and restoration of large amounts of data. Library automation provides economies of scale that individual drives can't by consolidating data, lowering total cost of ownership (TCO), reducing human intervention and error, simplifying backup and recovery, providing unattended lights-out backup and allowing a scalable growth path.
Tape library configuration
Before you can calculate a tape library's TCO, you need to choose the right combination of tape formats (see "A guide to tape formats") - which determines the capacity and transfer rate of individual drives - and the number of tape slots, which determines the total capacity of your library. The range available to you is quite broad: from autoloaders costing a couple of thousand dollars, to enterprise libraries in the hundreds of thousands of dollars (see "Scoping out tape library vendors").
The first step in automation is an autoloader. An autoloader, by definition, has one drive that typically serves seven or eight cartridges. An autoloader is good for unattended backup for a week or more for smaller companies. The newest versions are rack-mountable in a 2U format and have two drives - in case one fails.
This was first published in June 2002