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Understanding Device Abbreviations for
Different Tape Controllers and Media

You can have both SCSI and non-SCSI tape drives on the same system. A SCSI controller can have a maximum of eight SCSI tape drives, and a non-SCSI controller can have a maximum of four tape drives. For each drive number (X ), the density character depends on the controller and drive type, as described in the following paragraphs.

Table 3-2 shows the device abbreviations for different tape controllers/units and media. Note that the first character in the device abbreviation for drive number does not have to be 0 as shown, but could be 1, 2, or 3, and so on, depending on how many tape drives are attached to the system.

Table 3-2 Device Abbreviations for Tape Controllers/Units and Media
Controller Drive Unit Size Type Format Tracks Device Abbreviation
Xylogics 472 Fujitsu M2444 1/2-inch Reel 1600 bpi 9 /dev/rmt/0m
1/2-inch Reel 6250 bpi 9 /dev/rmt/0h
SCSI front-loaded HP 1/2-inch Reel 800 bpi 9 /dev/rmt/0m
6250 bpi 9 /dev/rmt/0h
SCSI Sysgen 1/4-inch Cartridge QIC-11 4 /dev/rmt/0l
QIC-24 4 /dev/rmt/0m
QIC-11 9 /dev/rmt/0l
QIC-24 9 /dev/rmt/0m
Emulex MT-02 1/4-inch Cartridge QIC-11 4 /dev/rmt/0l
QIC-24 4 /dev/rmt/0m
QIC-11 9 /dev/rmt/0l
QIC-24 9 /dev/rmt/0m
Archive QIC-150 1/4-inch Cartridge QIC-150 18 /dev/rmt/0h
Wangtek QIC-150 1/4-inch Cartridge QIC-150 18 /dev/rmt/0h
Desktop Backup Pack 1/4-inch Cartridge QIC-150 18 /dev/rmt/0h
Exabyte 8200 (2.3 Gbyte)*8 mm Cartridge 8 mm Helical scan /dev/rmt/0m
Exabyte 8500 (2.3 Gbyte)*8 mm Cartridge 8 mm Helical scan /dev/rmt/01
Exabyte 8500 (5 Gbyte)*8 mm Cartridge 8 mm Helical scan /dev/rmt/0m
Archive Python*4 mm Cartridge 4 mm Helical scan /dev/rmt/0
*New in this edition

Using Rack-Mounted Non-SCSI 1/2 - Inch Reel Drives

For 1/2 -inch rack-mounted tape drives with either a Tapemaster or Xylogics 472 controller, substitute the density from Table 3-3 for the A variable in the device name (/dev/rmt/XA).

Table 3-3 Designating Density for Rack-Mounted 1/2-Inch Tape Drives
Character Density
null Default "preferred" (highest) density (usually 6250 bpi uncompressed)
l 800 bpi
m 1600 bpi
h 6250 bpi
u 6250 bpi compressed

If you omit the density character, the tape is usually written at its highest density, not compressed.

Using SCSI 1/4 - Inch Cartridge and 1/2 - Inch Front-Loaded Reel Drives

For SCSI 1/4-inch cartridge and 1/2 -inch front-loaded reel drives, substitute the density from Table 3-4 for the A variable in the device name (/dev/rmt/XA).

Table 3-4 Designating Format or Density for SCSI Tape Drives
Character Density, 1/4-Inch Cartridge Density, 1/2-Inch Front-Loaded Reel-to -Reel
null Default, preferred (highest) density Default, preferred (highest) density
l QIC-11 format 800 bpi
m QIC-24 format 1600 bpi
h QIC-150 6250 bpi
u Reserved Reserved

For 1/4 -inch cartridges, density is specified by the format in which the data is written: the QIC format. The QIC-11 and QIC-24 formats write approximately 1000 bpi on each track. The density for QIC-150 is somewhat higher. The preferred density for a 60-Mbyte 1/4 -inch cartridge drive is QIC-24 and for a 150-Mbyte 1/4 -inch cartridge drive is QIC-150.

A 150-Mbyte drive can write only QIC-150; it cannot be switched to write QIC-24 or QIC-11. Format selection is only useful for drives that can write both QIC-24 and QIC-11.

Specifying Helical Scan Drives

Helical scan drives (for example, Exabyte 8 mm or Wang / DAT 4 mm) are a special case of SCSI drives. They write only at the preferred density. Consequently, you always specify them using only the drive number, for example, /dev/rmt/0.

Useful Commands for Streaming Tapes

The following sections contain a few commands for use with streaming tapes.


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