A tape drive, also known as a streamer, is a data storage device that reads and writes data stored on a magnetic tape. It is typically used for archival storage of data stored on hard drives. Tape media generally has a favorable unit cost and long archival stability.
Instead of allowing random-access to data as hard disk drives do, tape drives only allow for sequential-access of data. A hard disk drive can move its read/write heads to any random part of the disk platters in a very short amount of time, but a tape drive must spend a considerable amount of time winding tape between reels to read any one particular piece of data. As a result, tape drives have very slow average seek times. Despite the slow seek time, tapes drives can stream data to tape very quickly. For example, modern LTO drives can reach continuous data transfer rates of up to 80 MB/s, which is as fast as most 10,000 rpm hard disks.
An external QIC tape drive.
An external QIC tape drive.
Tape drives can be connected to a computer with SCSI (most common), Fibre Channel, FICON, ESCON, parallel port, IDE, USB, FireWire or other interfaces. Tape drives can range in capacity from a few megabytes to upwards of 800 GB. Tape drive storage is usually referred to with the assumption of 2:1 compression ratio, so a tape drive might be known as 80/160, meaning that the standard storage capacity is 80 whilst the compressed storage capacity can be up to 160. The raw storage capacity is known as the native capacity.
