6.3.7 Tape Housing Design  Two basic styles of housings are used, dual-hub cassettes, which may enable faster access times and single-hub cartridges, which offer greater capacity within a given external volume.  Dual hub cassettes include:

3.81mm, principally DDS [derived from DAT]
QIC [quarter-inch cartridge] and Travan
8mm formats, including Exabyte and AIT
Storagetek 9840  Single-hub cartridges include:

IBM MTC and Magstar formats such as 3590, 3592 and TS1120
Quantum S-DLT and DLT-S4
LTO Ultrium [100, 200, 400 & 800 GB]
Storagetek 9940 and T10000
Sony S-AIT  Neither design is necessarily superior for long-term archiving, since the life is governed by a range of details specific to each format.For instance,some models of the single-ended half-inch cartridges have large-diameter guides within the housing, which ensure minimum friction and accurate tape guidance. Problems have been experienced with the leader latching mechanism on older single-ended cartridges, although more recent designs have improved reliability in this area. Some dual-hub cassettes can be positioned to park halfway along the tape to minimise the amount of spooling time to any particular file. This contradicts the traditional practice in AV archives of spooling tapes carefully to one end before storage so that only leader tape is exposed to the threading mechanism. Tapes generally don’t incorporate a hermetically sealed enclosure in the way that hard disks are protected.