Using tapes

You can copy files to and from tape devices in the same way as you do with floppy disks. However, there are a number of differences between tapes and floppy disk systems. Notably, although magnetic tapes can store far more data than a floppy disk, they can only provide serial access to the information; that is, when reading or writing a tape, you must start at the beginning and read through each file until you get to the end: you cannot jump around or skip files.

To copy files to and from a tape device, you should use tar or cpio, with the appropriate device file (from the list below). You may also need to use the tape command to control the tape drive directly; see ``Rewinding, erasing, and retensioning tapes''.

There are several different types of tape that may be available on your machine. The following are the most common:

QIC-02

A full-sized quarter-inch tape cartridge; the first QIC-02 drive uses the /dev/rct0 device file. After accessing the tape, this device automatically rewinds the tape. If you store more than one archive on the tape, you must use the no-rewind device file /dev/nrct0 to access the second and subsequent files.

QIC-40/QIC-80

Smaller mini-cartridge units related to the QIC-02 format. These devices are accessed through the /dev/ft0 device file.

Mini-cartridge

Mini-cartridge tape drives linked to the floppy disk drive controller. These differ significantly from the QIC family of tape drives. Notably, you must format mini-cartridge tapes before using them (see ``Formatting tapes''). Mini-cartridge drives are accessed via the /dev/ctmini device file.

SCSI

SCSI tape drives are controlled by a SCSI controller; they are accessed via the devices named /dev/Stp0, /dev/Stp1, and so on.