• AIT

An acronym for Advanced Intelligent Tape, a magnetic tape and drive system used for computer data storage and archiving

• Areal Density

Important indicator of the performance of the disk and drive that corresponds to the number of magnetic bits per unit area

• AT Attachment Packet Interface (ATAPI)

A type of hardware interface widely used to connect hard disks, CD-ROMs and tape drives to a PC. Based on the IDE (Integrated Drive Electronics) interface, ATAPI defines the IDE standard for CD-ROMs and tape drives. ATAPI is currently the least expensive way to connect internal peripherals to a computer.

• Auxiliary Storage/
  External Storage/
  Secondary Storage

All addressable data storage that is not currently in the computer's main storage or memory

• Average access time

The average time required to begin reading data.

• Average swap time

The average time required to change and load a tape

• Backup

A snapshot or copy of data capable of being restored as necessary. backup application program A sequence of instructions that instructs the computer how to perform a backup, restore, or compare operation.

• Backward compatibility

The ability of a current product to read tapes written on earlier drives and, if so specified, to write tapes in the same format.

• Backup device

Typically, a tape drive used to store data or other information contained on a hard drive for the purpose of offline storage.

• BIOS (basic input/output system)

A collection of information (firmware) that controls communication between the central processing unit (CPU) and its peripherals.

• Bit

The smallest amount of information in a binary digital system that can be used to represent 2 states of information such as YES or NO

• Bit density

Expressed as bits-per-inch (BPI), bit density defines how many bits can be written onto one inch of a disc or tape track.

• Byte

Eight bits of information that can represent 256 different states, for example numbers, processor instructions, or a combination of letters and numbers as in ASCII code

• Capacity

The total amount of data, measured in gigabytes, that can be stored on a single data cartridge. The capacity of data cartridges always assumes that data can be written at a 2:1 compression ratio. Compressed Capacity: Effective capacity after data has been processed to reduce storage space required while maintaining data integrity - software and hardware compression are available. Uncompressed Capacity for data that has not been processed to reduce the effective size or volume; sometimes referred to as "native".

• CD-ReWritable

A compact disc that can be written, erased, and rewritten using optical methods. client/server Architecture where computing responsibility is distributed between front-end and back-end systems and programs.

• Compressed capacity

A measurement, usually in Gbytes, used to define the amount of space available to electronically store data after it has been processed to minimize its effective size while maintaining data integrity.

• Compression (data compression)

Digital data can be compressed by encoding repeatable patterns of binary 0's and 1's. Compression depends entirely on the type of file and compression algorithm used, and can be the result of a software algorithm or hardware circuitry. The more patterns that can be found, the more that data can be compressed. Text can generally be compressed to about 40% of its original size, and graphics files from 20% to 90%.

• DAFS

An acronym for Direct Access File System, a new file access protocol designed to take advantage of standard memory-to-memory interconnect technologies

• DAS

An acronym for Direct Attached Storage, those parts of a Wide Area Network in which the mass storage devices are connected locally

• DAT (Digital Audio Tape)

A magnetic tape technology for backing up data using helical scan recording. DAT uses 4mm cartridges that look like small audiocassettes and conform to the DDS (Digital Data Storage) standard. The DDS standard specifies the format and quality level of DAT technology for computer storage. With capacity points from 4-240GB, DAT or DDS is the industry standard in the workstation, PC and midrange server environments

• data transfer rate

The speed at which a tape drive can write digital data to a data cartridge. Transfer rates are usually measured in megabytes per minute and represent the highest sustainable speed at which the drive is able to operate.

• Data integrity

Ensuring that the data recorded on a tape cartridge can be restored to a disc drive in its original state. By using Error Correction Codes (ECC) and other techniques, Seagate tape drives automatically detect incorrectly recorded data and correct it to ensure accurate data restores. DDS (Digital Data Storage) A data-storage format that was developed from digital audio tape (DAT) to reliably store computer data. DDS is defined by international standards and is supported by many manufacturers, but more importantly, it is subject to thorough collaborative testing programs, which ensure that tapes (or media) written by one manufacturer's drives can be read by those of other manufacturers.

• Differential SCSI

The Differential SCSI interface allows longer cable lengths from the drive to the host with no degradation of signal. It is ideal for large server applications.

• Digital

Describes any system or subsystem that processes binary signals (values of 1 or 0 only). An example of a non-digital signal is an analog signal that continuously varies, such as RF or audio. DVD-RAM A high-density optical disc that can be written, erased, and rewritten by the user.

• DLT

An acronym for Digital Linear Tape technology, a form of magnetic tape and drive system used for computer data storage and archiving

• DVD-RAM

A high-density optical disc that can be written, erased, and rewritten by the user.

• Dynamic Powerdown

A Seagate technology that stores a small amount of power on the electronics of the tape drive and uses it to smoothly slow both tape reels down simultaneously when a power fault is detected. This feature is found on Viper 200, Seagate's LTO Ultrium format drive.

• ECC (error-correction code)

The incorporation of extra parity bits in stored data in order to detect errors that can be corrected by the drive when the data is read. ECC circuits correct data errors at the bit level.

• ElectroStatic Discharge (ESD)

Small static discharges that can destroy the circuitry of integrated circuits (chips). Personnel handling electronic equipment should ground themselves before touching the equipment. Electronic equipment should always be handled by the chassis or frame only.

• Enhanced IDE (Integrated Drive Electronics)

A high-speed, low cost interface to connect up to 4 devices found on 99% of PCs. Excellent interface for hard discs, tape drives and CD-ROMs. ethernet An access protocol that runs over coaxial or twisted pair wires with a typical data-transfer rate of 10 and 100 million bits per second.

• Exabyte

A unit of storage equal to 1,024 x 1,024 x 1,024 x Gigabytes = just over 1 billion Gigabytes.

• FastSense technology

A Seagate feature which optimizes backup time by allowing the tape drive to throttle its speed up or down to match the computer system's resources. This prevents "shoe-shining" or "back-hitching", i.e. the tendency for a drive to stop, rewind, and restart. FastSense also increases the life expectancy of a tape drive.

• FC

An acronym for Fibre Channel, an interface standard for connecting computers to mass storage devices such as disk drives and tape libraries

• Firmware

A computer program containing device-specific characteristics. If the code can be updated, it is said to be "flashable."

• GBIC

An acronym for GigaBit Interface Converter, an interface module which converts the light stream from a fibre channel cable into electronic signals for use by a network interface card

• Gigabyte

A unit of storage, abbreviated as G or GB, equal to 1,024 Megabytes

• Half-height drive

A drive that is 1.63 inches high.

• Hard disc drive

A device that stores data on and retrieves data from non-flexible (hard) rotating discs.

• Hardware data compression

Data compression can be performed either within the electronics of the tape drive (hardware data compression) or by the backup software application (software data compression). Having the tape drive perform the data compression operation frees the CPU from this task and improves the efficiency of the overall computer system.

• HBA

An acronym for Host Bus Adapter, an interface card which plugs into the computer's bus and connects it to the network

• Head

An electromagnetic device that can write/record, read/playback or erase data on magnetic media. Examples include: monolithic, composite, thin-film and magneto-resistive.

• Helical scan

A tape mechanism similar to a VCR's in which the heads are contained in a tilted, spinning drum. The tape is drawn halfway or further around the circumference of the drum, which reads or writes diagonally to the tape.

• Hot Plug/Hot Swap

The plugging in or removal of a drive into a system with the power turned on

• Hubs

Small reels holding the tape.

• HVD (High Voltage Differential)

A derivation of Ultra SCSI that allows for the use of data cable lengths up to 25 meters.

• Interface

The tape drive interface is the "language" or protocol a drive uses to communicate with a host computer or network. The main types of tape-drive interfaces used today include ATAPI (IDE), SCSI, and USB.

• iSCSI

Pronounced "iscuzzy," an acronym for Small Computer System Interface protocol over IP network instead of a direct SCSI compatible cable which enables data blocks to be read from or sent at high speed to a storage device such as a disk or tape drive

• JBOD

An acronym for Just a Bunch of Disks, a term used for a storage enclosure which is supplied with preintegrated disk drives

• Kilobyte (Kbyte)

Nominally refers to 1,000 bytes, especially when it is used to describe drive capacity. When used to describe semiconductor memory, however, it represents 1,024 bytes (2 to the 10th power)

• Linear

• Linear density

The number of bits per inch (bpi) stored on a tape.

• Local Area Network (LAN)

A series of computers connected into a system to allow communication and sharing of peripherals. Usually consists of a file server and one or more workstations.

• Low Voltage Differential (LVD)

See Ultra 2 SCSI.

• LTO

An acronym for Linear Tape-Open technology, developed jointly by HP, IBM, and Seagate, an "open format" technology, which means that users will have multiple sources of product and media

• LTO CM

A 64-Kbit memory chip built into the LTO tape cartridge for faster, more reliable access to data. Unlike conventional tape cartridges that must be rewound to the beginning of the tape to read the system log or find a desired file, LTO drives can use the memory in the cartridge to access that information immediately.

• Magneto-Optical (M-O)

A re-writable optical disc that uses a combination of magnetic and optical methods. MO disks use removable cartridges and come in two form factors -3.5" discs (up to 640-Mbyte) and 5.25" discs (up to 2.6-Mbyte per side). The 5.25" discs are double sided, but must be removed and flipped over.

• Mean Time Between Failure (MTBF)

The average time that a component is expected to work without failure. MTBF is the result of dividing the number of hours that a component is observed by the number of failures occurring during that period of time.

• Mean Time To Repair (MTTR)

The average time to repair a given unit. Limited to a qualified technician with proper equipment.

• Media

The magnetic layers of a disc or tape.

• Megabyte

A unit of storage abbreviated as M or MB, equal to 1,024 x 1,024 = 1,048,576 bytes

• Mirror Site

An exact replica of a website or set of files on a computer server that has been copied to another computer server to reduce network traffic, ensure better availability, or make access faster for local users (mirroring is the practice of creating and maintaining mirror sites)

• Model number

The drive Model number is Seagate's unique identifying code for each drive. The model number reflects the drive's form factor, capacity and interface.

• MR heads

Magnetoresistive heads - a technology in recording heads, which allows higher bit densities. This head consists of two elements: one for reading and another for writing.

• MSBF (Mean Swaps Between Failure)

A statistical calculation or number that loosely denotes the reliability of the robotics associated with tape autoloaders and libraries. The higher the MSBF, the more swap cycles (cartridge exchanges) the mechanism can be expected to perform without failure.

• Multitasking

The ability of a computer system to execute more than one program or program task at a time.

• Multiuser

The ability of a computer system to execute programs for more than one user at a time.

• NAS

An acronym for Network Attached Storage, a term used for RAID, tape and other mass storage systems which have an integral network connection such as ethernet or fibre-channel

• Native capacity

A measurement, usually in Gbytes, used to define the amount of space available to electronically store data without alteration, e.g. hardware or software compression

• Near-line storage

Data not immediately accessible by the host but available without human intervention (for example, a data-storage library system).

• Nibble

A unit of information equal to 4 Bits (or half a Byte)

• Node

Any computer on a network.

• Off-line

Processing or peripheral operations performed while not connected to the system CPU through the system BUS.

• Ongoing reliability testing (ORT)

Intended to establish the reliability of a product by an extended functional test under realistic user conditions.

• Open tape format specification

A specification that allows for compatible and interchangeable, but technologically independent tape products to be marketed. Typically, the technology owners will license the technology to various manufacturing partners. The benefits of an open format are multiple, interchangeable sources of supply, strong competition between format products, lower pricing and faster technology innovation. Examples are Travan, DDS and LTO technology.

• Operating system

An operating system is a program that acts as an interface between the user of a computer and the computer hardware. The purpose of the operating system is to provide an environment in which a user can run programs.

• Parallel

A type of recording in which a byte or group of bytes are recorded simultaneously in a vertical line crossing all the tracks on the tape.

• Peripheral equipment

Auxiliary memory, displays, printers, disc drives, tape drives and other equipment usually attached to the computer system CPU by controllers and cables (they are often packaged together in a desktop computer).

• Petabyte

A unit of storage equal to 1,024 Terabytes, or just over a million Gigabytes

• Printed circuit board (PCB)

The circuit board with integrated circuits (chips) attached.

• Printed wire assembly (PWA)

A completed circuit board with components installed. (Same as PCB)

• Printed wire board (PWB)

A circuit board without components installed, also known as a bare board. PRML Partial-response, maximum likelihood - advanced technology read channel that contributes to a faster data throughput rate.

• PRML

Partial-response, maximum likelihood - advanced technology read channel that contributes to a faster data throughput rate.

• Protocol

A set of rules governing the format of messages exchanged within a communications system.

• QIC (Quarter-Inch Cartridge)

Defines a standards committee and a variety of tape formats.

• RAID

Originally, an acronym for Redundant Array of Inexpensive Disks to reflect the data accessibility and cost advantages that properly implemented arrays could provide, the acronym has evolved to mean Redundant Array of Independent Disks emphasizing the technique's potential data availability advantages over conventional disk storage systems

• Random access memory (RAM)

Memory where any location can read from or write to in random order. RAM usually refers to volatile memory where the contents are lost when power is removed. The user-addressable memory of a computer is random access memory.

• Read only memory (ROM)

A chip that can be programmed once with bits of information. This chip retains the information even if the power is turned off. When the information is programmed into the ROM, it is called burning the ROM.

• Restore

Retrieval of information from a tape drive and the recording of it on a disc drive.

• Read While Write (RWW)

A method whereby data being recorded onto tape is read and verified on the same pass as it is written. The ability of a tape drive to write data to tape and immediately read it from the tape and compare it to the original data in the drive's buffer during the same pass of the tape.

• SAN

An acronym for Storage Area Network, a high-speed network that is typically part of an overall network of computing resources for an enterprise, in which the software knows the characteristics of storage devices and the quantity and value of data stored in those devices

• SCSI (Small Computer Systems Interface)

Pronounced "scuzzy," an acronym for Small Computer System Interface, a high performance parallel interface for connecting mass storage devices, usually hard discs, tape drives, and CD-ROMs.

• SDLT/SuperDLT

An acronym for Super Digital Linear Tape technology, a variant of DLT technology that makes it possible to store upwards of 100 GB on a single cartridge and can transfer data at speeds of up to 10 megabytes per second

• Serial

A type of recording in which each byte is recorded one bit at a time on a single track.

• Serpentine

An efficient recording method that records one track with the tape running in one direction, the next lowest track with the tape running the opposite direction, and so on. server A computer deliberately devoted to sharing its files and resources, such as discs and printers, with other computers on the network.

• Server

A computer deliberately devoted to sharing its files and resources, such as discs and printers, with other computers on the network.

• SNIA

An acronym for Storage Networking Industry Association, a non-profit trade organization, incorporated in December 1997 whose members are dedicated to "ensuring that storage networks become complete and trusted solutions across the IT community"

• Speed

The maximum sustained data transfer rate that a tape drive can provide, assuming that the data on the tape is stored in compressed form at a 2:1 compression ratio.

• Storage Consolidation

The concept of centralizing and sharing storage resources among many application servers

• TCP/IP (transmission control protocol/internet protocol)

A set of protocols used on the Internet to connect dissimilar computers and offer services such as Telnet and FTP.

• Terabyte

A unit of storage, abbreviated as T or TB, equal to 1,024 Gigabytes

• Travan

Tape technology, based on linear recording, with capacity points from 8-40 Gbytes, represents an efficient cartridge and drive design that reduces tape stress, ensures data integrity and increases drive and cartridge reliability. Travan mechanisms are known to be very reliable at a cost-effective price point and are the perfect choice for PCs, workstations and entry-level server environments. Seagate offers bare Travan drives called Hornet Travan and bundled solutions called TapeStor Travan.

• Travan / Travan NS

A backup tape technology that evolved from Quarter Inch Cartridge (QIC). Travan uses wider tape, different tape guides, and improved magnetic media to yield higher capacities. Travan Network Series (NS) is a migration from desktop to workgroup server backup and provides hardware compression and read-while-write features. Depending on the model, Travan drives may be compatible with QIC, QIC-Wide and QIC-EX cartridges.

• Ultra ATA

Industry-accepted standard that allows a maximum data transfer rate of 33 Mbytes per second using an ATA (IDE) interface.

• Ultra SCSI

Ultra SCSI is an evolution of the standard SCSI interface. Sometimes referred to as Fast 20, Ultra SCSI enables external transfer rates of up to 20 Mbytes per second on an 8-bit bus and up to 40 Mbytes per second on a 16-bit bus. Ultra SCSI uses the same physical connections as SCSI-2 and is fully backward compatible. To reach the maximum transfer rates of up to 20 (8-bit) or up to 40 (16-bit) Mbytes per second, the controller and disc drive both must be Ultra SCSI devices. Ultra SCSI also reduces total cable lengths to half of the Fast SCSI-2 specification. Ultra SCSI represents the parallel SCSI solution defined in the SCSI-3 ANSI standard specification.

• Ultra2 SCSI

Provides bus data rates of 80 Mbytes per second and easy integration of up to 16 devices on the SCSI bus using cable lengths of 12 meters. Low Voltage Differential doubles SCSI bus rates and provides the integration flexibility and data integrity of High Voltage Differential at single-ended costs. Ultra2 SCSI LVD is fully backward compatible to all previous single-ended versions of SCSI, taking advantage of the previously installed multibillion-dollar product base. When an Ultra2 drive is installed on a previous version SCSI bus, performance will de-fault to the specifications of that bus.

• Ultrium format

The high capacity format used in Linear Tape-Open technology. The Ultrium format specifies those technologies required for consistent and reliable data interchange between drives manufactured to the Ultrium specification. The Ultrium format provides for up to 200 Gbytes of compressed (2:1) data storage per cartridge on half-inch tape. Also specified is a compressed (2:1) transfer rate of up to 40 Mbytes per second. Also see Linear Tape-Open technology. Using a single-reel tape cartridge to maximize capacity, the Ultrium tape format is ideally suited for backup, restore and archive applications. Seagate provides Ultrium format tape drives through its Viper family.

• Uncompressed Native

e.g. data that has not been processed to reduce the effective size or volume; or unaltered, e.g. compressed data that has been processed to restore redundant strings of data previously removed through the use of a compression algorithm.

• Unformatted

Drive byte capacity before formatting. Maximum capacity of a disc drive before formatting, which is equal to bits per track times the number of heads times the number of cylinders.

• USB (Universal Serial Bus)

Universal Serial Bus (USB) is the simple way to connect peripherals to your computer. It can be used to attach a wide variety of devices like scanners, cameras, keyboards, and speakers - almost anything to your computer. A USB is great for attaching medium speed devices to computers. It's maximum speed of 12 Mbps is fine for low speed devices like keyboards, mice, or joysticks. It is also well suited for medium speed devices like tape drives, hard disc drives, cameras, modems, or scanners. Also, because it's "hot-pluggable" you can plug devices in or unplug them safely when you computer is turned on. Using either multiple ports on your computer or a hub, you can attach an almost unlimited number of devices - theoretically up to 127 if you have them.

• Verification

This feature lets the backup software application compare the data written to the original information to the data was written correctly.

• Virtualization

The pooling of physical storage from multiple network storage devices into what appears to be a single storage device that is managed from a central console

• Volatile

Memory that will be erased if power is lost. Typically, main memory is volatile.

• Vsnap

Virtual snapshot: space-efficient snapshot available on Enterprise Virtual Array family products