Almost all multi-user automated library systems now include a cartridge tape drive, usually a 4mm or 8mm unit. We have frequently urged that these drives be sized to equal the total amount of disk storage on a library's system so that a complete database back-up or a database “dump” can be undertaken without staff having to remain near the system to change tapes. For many libraries that has meant spending several thousand dollars on a tape drive with considerably more capacity than needed. Often a library needing just a little more than 2.0GB may have been required to purchase a 5.0, 8.0, or 10GB cartridge tape drive.
There is now a more attractive alternative: a compressible tape drive. Using standard hardware data-compression techniques, it is possible to double a drive's storage capacity without adversely affecting performance or file security. Data compression works by reducing the size of the records through the elimination of empty fields and unnecessary data.
The equivalent to the 2.0GB drive is a 2.0-4.0GB compressible unit offering most libraries more than enough capacity at basically the same price as a 2.0GB unit. For libraries requiring more than 4.0GB of storage there is a 4.0-8.0GB compressible unit, which is less expensive than a 5.0 or an 8.0GB drive. While not all product lines have the same capacities—for example, a number of product lines have a 2.7GB cartridge drive, rather than a 2.0GB, virtually all lines include compressible drives which offer double the capacity of the regular drives.