In data storage, a tape library is a collection of magnetic tape cartridges and tape drives.
Tape libraries vary widely in cost and complexity. A typical library contains multiple tape drives for reading and writing data, access ports for entering and removing tapes, bar codes to track the tapes, and a device for mounting and dismounting tape cartridges. A library can include thousands of tapes.
Although tape drives have improved in features and reliability, the concept of writing data to magnetic tape has not changed for decades.
A tape library and its features must be compatible with the rest of an organization's data protection system, including the backup software. Tape library vendors provide compatibility lists of which backup software and hardware will work with their products.
In determining specifications for a tape library, an organization must typically figure out how big the library backup or archival set will be, including factoring in data growth.
Though advances in technologies, such as large-capacity disk drives and the cloud, have made tape less fashionable as a backup device, it is still a popular choice for archiving. The Linear Tape File System (LTFS), for example, puts a file system on top of a tape library, improving its suitability for archive use cases.
Organizations of all sizes use tape libraries. A large enterprise will often use a tape library as a secondary backup target or an archive, if not as a primary backup means.
A tape library's cost is generally less than disk or flash systems. Disk, for example, is expensive for archiving because of both upfront and operational costs.
Tape is also attractive for its durability and shelf life. In a disaster recovery situation, tape is a useful tool for retrieving data.
Encryption is offered for data security with tape libraries. In a common scenario, a backup media server, tape library, virtual tape library (VTL) or individual tape drive encrypts data as it is written. Encryption is especially important when tapes go off site because it protects the data in the event of a lost or stolen tape.
Tape libraries contain the capacity for massive amounts of information that is rarely accessed or changed. For example, one LTO-7 tape cartridge holds up to 6 terabytes (TB) of native capacity, or 15 TB compressed. With the explosion of data surpassing multiple zettabytes, enterprises often turn to tape for long-term archiving. Retrieval of data from a large backup tape library can be faster than retrieving data from the cloud.
Though LTFS has improved filing systems and accessibility, a tape library can't match the access speeds of other technologies, such as disk. Because of the sequential nature of tapes, a user must roll through a tape to locate specific data.
Tape libraries can get complex, requiring management by the system's backup software. Support is also a concern. As technologies develop, an organization must ensure its tape library is compatible with all the other necessary components. For example, old tape drives may not work with a new library.
Tape libraries and autoloaders automate backups and archives with multiple tapes. Tape libraries offer more capabilities than autoloaders, but are often far more expensive, as well as more complex because they have more tape drives.
A tape autoloader is a step up from a single tape drive for backup and archiving. Backup tape autoloaders provide automatic tape exchanges and more reliability than a stand-alone drive, but still have a limited capacity compared to tape libraries.
A tape autoloader typically consists of a tape drive, a tape magazine and a robotic arm that moves tapes between the drive and the magazine. The bigger tape library has multiple drives, and the robotic tape loader can access all of them, improving reliability. For example, if one tape drive in a library fails, the library could continue operation by using a different drive.
In hierarchical tape library storage management, the library removes rarely accessed files from network volumes and archives them to tapes. The library identifies where files live with barcodes. For retrieval, the robotic tape loader verifies that it is accessing the correct tape. Tape libraries are getting denser and, thanks to robotics, access speed continues to improve.
In the LTFS Library Edition, each cartridge's file system is logically presented with an overarching file system. The library's robotics mounts a given cartridge, which is transparent to users.
A VTL is a hard disk drive-based storage system. It is designed to make disk storage look like a physical tape library to backup software. As with physical tape, data is written sequentially to a VTL, but can be written and read faster because it's on disk. Virtual tape libraries are frequently used for backup and archiving.
Because backup software historically didn't support the use of disk-based backup targets, VTLs enabled disk storage to be used for backup by posing as a tape library. Disk enables faster backup and recovery and more frequent backups.
VTLs and disk-to-disk backups are often packaged together with data deduplication. Both technologies will typically attach to a backup media server that manages them.
StorageTek -- now part of Oracle -- is widely credited with inventing the first library to handle tapes more efficiently.
Modern enhancements from tape library vendors include the following:
Other tape library vendors include Dell Technologies and Hewlett Packard Enterprise.
Because of the large storage capacity of tape libraries, some organizations bring them in for heavy duty data storage projects. Some high-profile uses of tape libraries include the following:
17 Apr 2023