Tape Storage Category
An explanation of terms related to tape storage devices
- Data block written at the front of a volume to identify it.
- Keeping a recording of each of a succession of versions, or revision levels, of a file or document.
- Action of comparing the data read to data written. Verification provides an additional confidence check.
- Data recorded by the user. User data is differentiated from other information recorded by either the drive or formatter.
- High capacity minicartridge technology developed by Imation Corporation (formerly a division of 3M Company).
- Data cartridge drive that writes or reads blocks without stopping between blocks.
- A bi-directional recording scheme; recording of one track in a forward direction is followed by recording the next track in a reverse direction.
- A closed-loop control system used to adjust head position and/or tape speed.
- Winding the tape from the beginning of tape (BOT) to the end of tape (EOT), or EOT to BOT. Ensures that the tape in the cartridge is correctly tensioned and will ensure optimum head-to-tape contact for error-free performance.
- Retrieving information from a tape drive in order to replace data that was lost from a hard disk.
- Restoring files from tape to a hard disk location that is different from where they were originally backed-up.
- Number of flux transitions written at the beginning of the tape to indicate the centre line of the tape. This allows the read head of the drive to align itself correctly and improves the data integrity of the drive.
- The definition of how data is written to the tape. It defines such things as the number and position of tracks, bits per inch and the recording code to be used.
- Quarter-Inch Cartridge Drive Standards: an international trade association comprised of manufacturers of QIC tape drives, media and critical components with primary charters to identify market needs; educate users, OEMs, system integrators, resellers and dealers; and provide a forum for technical discussions leading to the generation of development standards for compatibility among manufacturers’ systems.
- Quick File Access: a method of locating files quickly using high tape speeds.
- Section of recorded data used to synchronise the data decoding electronics to the data stream. It occurs at the start of the data block.
- Section of recorded data used to synchronise the data decoding electronics to the data stream. It occurs at the end of the data block.
- Address on all formatted QIC tapes, data is recorded in physical blocks which are numbered sequentially from the BOP and whose size is fixed by the recording format standard. The number of each physical block is unique and may be used as an address to locate data.
- Phase Encoding: method of coding data; it has the advantage of being very reliable and easy to decode, but it is not particularly efficient in data density.
- Method of overwriting data on a tape without first erasing it.
- Oe: the measurement of force required to produce a change in the magnetic state of media. Higher numbers equate with higher packing density and increased capacity. See also Coercivity.
Off Track Retry
- Method of improving data recovery under error conditions. It is often possible to recover a data error by moving the head slightly off the track centre and re-reading the block.
- Capacity for data that has not been processed to reduce the effective size or volume. Also called uncompressed capacity.
- Exabyte Corporation’s new high-performance, high-capacity 8mm tape backup technology.
- Load Point: the physical location on the tape where data recording starts. This location is physically marked by the location of a punched hole.
Linear Recording Density
- Measurement of amount of data stored in a given length of tape; usually expressed in bits per inch (BPI).
- Instantaneous Speed Variation: the fluctuation of speed of recording tape over extremely short periods of time.
- To retension and read or write header blocks before a data cartridge is used.
- The first tape segment where the tape format information resides, such as tape name, date, time and bad sector map.
- A method of reading and writing data to tape using a rotating head/drum assembly.
- Group Code Recording: a particular code of the RLL data encoding method often used on data cartridge drives. The code combines high data density with relative ease of decoding.
- Flux Reversals Per Inch: the number of flux changes per inch of tape. This may or may not be equal to the number of bits per inch stored, depending on the recording code in use. Also referred to as Flux Transitions Per Inch (FTPI).
- A change in magnetic polarity in the tape media which, through a magnetic head and a tape drive’s read circuitry, is translated into a data bit. Typically expressed in FRPI or FTPI.
- Early Warning: a way that the data cartridge indicates to the drive that the end of the tape is approaching. Technically, the first hole in the EOT hole pattern. This allows drive electronics to take the appropriate actions.
- To remove previously-written data by randomising the magnetic orientation of the media.
- End of Data: location on tape after which no information is recorded.
- End of Partition: on tapes which are partitioned into logical volumes, the EOP is treated as the End of Tape for that volume. A volume has only one EOT but has as many EOPs as partitions. See also BOP.
- End of Tape: designated by a specific hole pattern on quarter-inch cartridge tape media.
- Method of using the recording head to detect the edge of tape and then to reference the tracks from the edge of tape, thus assuring the tracks are positioned accurately.
- Digital Linear Tape: a half-inch wide magnetic tape backup technology originally developed by Digital Equipment Corporation and which has grown rapidly since its acquisition by Quantum Corporation in 1994.
- Digital Audio Tape: initially a CD-quality audio format which recorded at 41.8kHz. In 1988, Sony and HP defined the Digital Data Storage (DDS) standard enabling DAT to become a magnetic tape technology used for backing up data.
- Effective capacity after data has been processed to reduce storage space required while maintaining data integrity. Software and hardware compression are available.
- The field strength required to change the magnetic state of magnetic material; expressed in Oersteds.
- Command Descriptor Block: a command data block issued from a host to a target peripheral containing the operation to be performed and the parameters associated with that operation.
- A case containing multiple components including recordable tape. QIC media for the 5.25-inch form factor is a data cartridge; QIC media for the 3.5-inch form factor is a minicartridge.
- Beginning of Tape: designated by a specific hole pattern on quarter-inch cartridge tape media.
- Beginning of Partition: on tapes partitioned into logical volumes, the BOP is treated as the Beginning of Tape (BOT) for that volume. A tape has only one BOT, but has as many BOPs as partitions.
- Areas on the tape that cannot reliably retain data. This information is held in the tape header block.
- Advanced Metal Evaporated: media with a film of metallic recording material deposited by an evaporative process.
Advanced Intelligent Tape – AIT
- An advanced 8mm tape backup technology sponsored by Sony and Seagate.
- A high-capacity magnetic tape technology developed by Exabyte Corporation, for backing up data and first introduced in 1987.