Computer data storage is a technology consisting of computer components and recording media that are used to retain digital data. It is a core function and fundamental component of computers.
Disk storage is a general category of storage mechanisms where data is recorded by various electronic, magnetic, optical, or mechanical changes to a surface layer of one or more rotating disks. A disk drive is a device implementing such a storage mechanism. Notable types are the hard disk drive (HDD) containing a non-removable disk, the floppy disk drive (FDD) and its removable floppy disk, and various optical disc drives (ODD) and associated optical disc media.
A tape drive is a data storage device that reads and 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 a long archival stability.
In computing and optical disc recording technologies, an optical disc (OD) is a flat, usually circular disc that encodes binary data (bits) in the form of pits and lands on a special material on one of its flat surfaces.
A magneto-optical drive is a kind of optical disc drive capable of writing and rewriting data upon a magneto-optical disc. Both 130 mm (5.25 in) and 90 mm (3.5 in) form factors exist. In 1983, just a year after the introduction of the Compact Disc, Kees Schouhamer Immink and Joseph Braat presented the first experiments with erasable magneto-optical Compact Discs during the 73rd AES Convention in Eindhoven. The technology was introduced commercially in 1985. Although optical, they appear as hard disk drives to the operating system and can be formatted with any file system. Magneto-optical drives were common in some countries, such as Japan, but have fallen into disuse.
A USB flash drive is a data storage device that includes flash memory with an integrated USB interface. It is typically removable, rewritable and much smaller than an optical disc. Most weigh less than 30 g (1 oz). Since first appearing on the market in late 2000, as with virtually all other computer memory devices, storage capacities have risen while prices have dropped. As of March 2016, flash drives with anywhere from 8 to 256 gigabytes (GB) were frequently sold, while 512 GB and 1 terabyte (TB) units were less frequent. As of 2018, 2 TB flash drives were the largest available in terms of storage capacity. Some allow up to 100,000 write/erase cycles, depending on the exact type of memory chip used, and are thought to last between 10 and 100 years under normal circumstances.
Non-volatile memory (NVM) or non-volatile storage is a type of computer memory that can retrieve stored information even after having been power cycled. In contrast, volatile memory needs constant power in order to retain data. Examples of non-volatile memory include flash memory, read-only memory (ROM), ferroelectric RAM, most types of magnetic computer storage devices, optical discs, and early computer storage methods such as paper tape and punched cards.
Digital Linear Tape is a magnetic tape data storage technology developed by Digital Equipment Corporation (DEC) from 1984 onwards. In 1994, the technology was purchased by Quantum Corporation, who manufactured drives and licensed the technology and trademark. A variant with higher capacity is called Super DLT (SDLT). The lower cost "value line" was initially manufactured by Benchmark Storage Innovations under license from Quantum. Quantum acquired Benchmark in 2002.
Magnetic storage or magnetic recording is the storage of data on a magnetized medium. Magnetic storage uses different patterns of magnetisation in a magnetisable material to store data and is a form of non-volatile memory. The information is accessed using one or more read/write heads.
Travan is an 8 mm magnetic tape cartridge design developed by the 3M company, used for the storage of data in computer backups and mass storage. Over time, subsequent versions of Travan cartridges and drives have been developed that provide greater data capacity, while retaining the standard 8 mm width and 750' length. Travan is standardized under the QIC body. HP Colorado, Iomega DittoMax and AIWA Bolt are proprietary versions of the Travan format.
Areal density is a measure of the quantity of information bits that can be stored on a given length of track, area of surface, or in a given volume of a computer storage medium. Generally, higher density is more desirable, for it allows more data to be stored in the same physical space. Density therefore has a direct relationship to storage capacity of a given medium. Density also generally affects the performance within a particular medium, as well as price.
The Holographic Versatile Disc (HVD) is an optical disc technology developed between April 2004 and mid-2008 that can store up to several terabytes of data on an optical disc 10 cm or 12 cm in diameter. The reduced radius reduces cost and materials used. It employs a technique known as collinear holography, whereby a green and red laser beam are collimated in a single beam. The green laser reads data encoded as laser interference fringes from a holographic layer near the top of the disc. A red laser is used as the reference beam to read servoinformation from a regular CD-style aluminium layer near the bottom. Servoinformation is used to monitor the position of the read head over the disc, similar to the head, track, and sector information on a conventional hard disk drive. On a CD or DVD this servoinformation is interspersed among the data. A dichroic mirror layer between the holographic data and the servo data reflects the green laser while letting the red laser pass through. This prevents interference from refraction of the green laser off the servo data pits and is an advance over past holographic storage media, which either experienced too much interference, or lacked the servo data entirely, making them incompatible with current CD and DVD drive technology.
In computing, external storage comprises devices that store information outside a computer. Such devices may be permanently attached to the computer, may be removable or may use removable media.
Holographic data storage is a potential technology in the area of high-capacity data storage. While magnetic and optical data storage devices rely on individual bits being stored as distinct magnetic or optical changes on the surface of the recording medium, holographic data storage records information throughout the volume of the medium and is capable of recording multiple images in the same area utilizing light at different angles.
Ultra Density Optical (UDO) is an optical disc format designed for high-density storage of high-definition video and data.
Magnetic tape data storage is a system for storing digital information on magnetic tape using digital recording. Initially, large open reels were the most common format, but modern magnetic tape is most commonly packaged in cartridges and cassettes, such as the widely supported Linear Tape-Open (LTO). The device that performs the writing or reading of data is called a tape drive, and autoloaders and tape libraries are often used to automate cartridge handling.
3D optical data storage is any form of optical data storage in which information can be recorded or read with three-dimensional resolution.
The IBM 3592 is a series of tape drives and corresponding magnetic tape data storage media formats developed by IBM. The first drive, having the IBM product number 3592, was introduced under the nickname Jaguar. The next drive was the TS1120, also having the nickname Jaguar. As of November 2018, the latest and current drive is the TS1160 Gen 6. The 3592 line of tape drives and media is not compatible with the IBM 3590 series of drives, which it superseded. This series can store up to 20 TB of data (uncompressed) on a cartridge and has a native data transfer rate of up to 400 MB/s.
LV-ROM is an optical disc format developed by Philips Electronics to integrate analog video and computer software for interactive multimedia. The LV-ROM is a specialized variation of the CAV Laserdisc. LV-ROM is an initialism for "LaserVision Read-Only Memory".
Optical Disc Archive is a proprietary storage technology that was introduced by the Sony Corporation. It uses removable cartridges, where each cartridge holds 11 optical discs. Each of the internal optical discs is similar to, but not compatible with, a Blu-ray disc. The latest version of the cartridge, that has a total capacity of about 5.5TB, uses discs that hold about 500GB each. The technology was publicly announced on 16 April 2012 during the NAB Show with the first units shipping in February 2013.
