Tape library
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In computer storage, a tape library, sometimes called a tape silo, or tape jukebox, is a storage device which contains one or more tape drives, a number of slots to hold tape cartridges, a barcode reader to identify tape cartridges and an automated method for loading tapes (a robot). One of the earliest examples was the IBM 3850 Mass Storage System (MSS), announced in 1974.
These devices can store immense amounts of data, currently ranging from 20 terabytes[1] up to more than 50 petabytes of data,[2] or about one hundred thousand times the capacity of a typical hard drive and well in excess of capacities achievable with network attached storage. Typical entry-level solutions cost around $10,000 USD,[3] while high-end solutions can cost in excess of $70,000 USD[4] For large data-storage, they are a highly cost-effective solution, with cost per gigabyte as low as 10 cents USD, or at least 60% less than most hard drives, and they also add the value of providing systematic access to very large quantities of data. The tradeoff for their larger capacity is their slower access time, which usually involves mechanical manipulation of tapes. Access to data in a library takes from several seconds to several minutes.
Because of their slow random access and huge capacity, tape libraries are primarily used for backups and as the final stage of digital archiving. A typical application of the latter would be organization's extensive transaction record for legal or auditing purposes. Another example is hierarchical storage management (HSM), in which tape library is used to hold rarely used files from file systems.
Smaller tape libraries with only one drive and robot are known as autoloaders.
[edit] Software support
There are several large-scale library-management packages available commercially. Open-Source support includes AMANDA and the minimal mtx program.
Most libraries have the capability of scanning barcode labels, allowing them to locate the correct tape even if it is not in the expected slot. Preprinted labels are available commercially but may also be generated using software such as HP DLT 4000 Barcode Labels.
[edit] Dominant tape library manufacturers and brands
- BDT AG
- IBM: TS3310, TS3500, 3582, 3583, 3584, 3494
- Overland Storage
- Quantum (acquired ADIC in 2006)
- Spectra Logic
- Sun Microsystems (acquired StorageTek in 2005): L25, L100, L180, L500, L700, L8500.
- Tandberg Data (acquired Exabyte): StorageLibrary T40
