Tape library
Encyclopedia
In computer storage
, a tape library, sometimes called a tape silo, tape robot or tape jukebox, is a storage device which contains one or more tape drive
s, 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 terabyte
s up to more than 366 petabyte
s of data, or about seven 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, while high-end solutions can start at as much as $200,000 USD and cost well in excess of $1 million for a fully expanded and configured library. For large data-storage, they are a 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 provide 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 sequential access and huge capacity, tape libraries are primarily used for backup
s and as the final stage of digital archiving
. A typical application of the latter would be an 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 system
s.
, Bacula
, and the minimal mtx program.
, information recorded at the beginning of the media to uniquely identify the tape.
Smaller tape libraries with only one drive are known as autoloaders. The term autoloader is also sometimes used synonymously with stacker, a device in which the media is loaded necessarily in a sequential manner.
Other types of autoloaders may operate with optical disks, floppy disk
s and compact disc
s.
Computer storage
Computer data storage, often called storage or memory, refers to computer components and recording media that retain digital data. Data storage is one of the core functions and fundamental components of computers....
, a tape library, sometimes called a tape silo, tape robot or tape jukebox, is a storage device which contains one or more tape drive
Tape drive
A tape drive is a data storage device that reads and performs digital recording, writes data on a magnetic tape. Magnetic tape data storage is typically used for offline, archival data storage. Tape media generally has a favorable unit cost and long archival stability.A tape drive provides...
s, a number of slots to hold tape
Magnetic tape data storage
Magnetic tape data storage uses digital recording on to magnetic tape to store digital information. Modern magnetic tape is most commonly packaged in cartridges and cassettes. The device that performs actual writing or reading of data is a tape drive...
cartridges, a barcode
Barcode
A barcode is an optical machine-readable representation of data, which shows data about the object to which it attaches. Originally barcodes represented data by varying the widths and spacings of parallel lines, and may be referred to as linear or 1 dimensional . Later they evolved into rectangles,...
reader to identify tape cartridges and an automated method for loading tapes (a robot). One of the earliest examples was the IBM 3850
IBM 3850
The IBM 3850 Mass Storage System was an online tape library used to hold large amounts of infrequently accessed data.- History :Starting in the late-1960s IBM's lab in Boulder, Colorado began development of a low-cost mass storage system based on magnetic tape cartridges...
Mass Storage System (MSS), announced in 1974.
These devices can store immense amounts of data, currently ranging from 20 terabyte
Terabyte
The terabyte is a multiple of the unit byte for digital information. The prefix tera means 1012 in the International System of Units , and therefore 1 terabyte is , or 1 trillion bytes, or 1000 gigabytes. 1 terabyte in binary prefixes is 0.9095 tebibytes, or 931.32 gibibytes...
s up to more than 366 petabyte
Petabyte
A petabyte is a unit of information equal to one quadrillion bytes, or 1000 terabytes. The unit symbol for the petabyte is PB...
s of data, or about seven 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, while high-end solutions can start at as much as $200,000 USD and cost well in excess of $1 million for a fully expanded and configured library. For large data-storage, they are a 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 provide 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 sequential access and huge capacity, tape libraries are primarily used for backup
Backup
In information technology, a backup or the process of backing up is making copies of data which may be used to restore the original after a data loss event. The verb form is back up in two words, whereas the noun is backup....
s and as the final stage of digital archiving
Archive
An archive is a collection of historical records, or the physical place they are located. Archives contain primary source documents that have accumulated over the course of an individual or organization's lifetime, and are kept to show the function of an organization...
. A typical application of the latter would be an organization's extensive transaction record for legal or auditing purposes. Another example is hierarchical storage management
Hierarchical storage management
Hierarchical storage management is a data storage technique which automatically moves data between high-cost and low-cost storage media. HSM systems exist because high-speed storage devices, such as hard disk drive arrays, are more expensive than slower devices, such as optical discs and magnetic...
(HSM), in which tape library is used to hold rarely used files from file system
File system
A file system is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device which contain it. A file system organizes data in an efficient manner and is tuned to the...
s.
Software support
There are several large-scale library-management packages available commercially. Open-Source support includes AMANDAAdvanced Maryland Automatic Network Disk Archiver
Amanda, previously known as Advanced Maryland Automatic Network Disk Archiver is an open source computer archiving tool that is able to back up data residing on multiple computers on a network...
, Bacula
Bacula
Bacula is an open source, enterprise level computer backup system for heterogeneous networks. It is designed to automate backup tasks that had often required intervention from a systems administrator or computer operator....
, and the minimal mtx program.
Barcode labels
Tape libraries commonly have the capability of optically scanning barcode labels which are attached to each tape, allowing them to automatically maintain an inventory of which tapes are where within the library. Preprinted barcode labels are commercially available or custom labels may be generated using commercial or free software. The barcode label is frequently part of the tape labelTape label
Tape labels are identifiers given to volumes of magnetic tape.There are two kinds of tape labels. The first is a label applied to the exterior of tape cartridge or reel. The second is data recorded on the tape itself.-Visual labels:...
, information recorded at the beginning of the media to uniquely identify the tape.
Autoloaders
Other types of autoloaders may operate with optical disks, floppy disk
Floppy disk
A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...
s and compact disc
Compact Disc
The Compact Disc is an optical disc used to store digital data. It was originally developed to store and playback sound recordings exclusively, but later expanded to encompass data storage , write-once audio and data storage , rewritable media , Video Compact Discs , Super Video Compact Discs ,...
s.