Seagate STT20000N, Product Manual

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Tape format Chapter 6
STT20000N Product Manual Page 45
Tape format
Introduction
The STT20000 SCSI minicartridge drive conforms to the QIC-3220-MC recording
format standard. This format is for streaming magnetic tape in a minicartridge that is
to be used for information interchange among information processing systems,
communication systems, and associated equipment.
This chapter provides an overview of the tape format used by the SCSI
Minicartridge drive.
Tape partitioning
The drive uses factory pre-written Travan TR-5 (or Travan NS-20) media. The tape
is always divided into two partitions:
•
Partition 1 is the directory partition and is recorded on the Directory track only.
•
Partition 0 contains the data (tracks 0 through 107) and is recorded on all tracks
except the Directory track.
Recording data at 100,400 bits per inch (BPI), the drive can store 10.0 Gbyte on the
data partition of 740-foot long, 0.315-inch (8.0 mm) wide Travan TR-5 tape. Using
data compression, this capacity is up to twice the native storage capacity.
The recording format and partitioning support Quick File Access (QFA).
Track positions
The centermost track is called the Directory Track and has larger guard bands on
both sides of it to allow it to be written without interfering with its adjacent tracks.
Track zero is the track immediately below the Directory Track. The even numbered
tracks are positioned sequentially below track 0. Thus, track 2 is below track 0, and
track 4 is below track 2, and so on down to track 70, which is the closest to the
reference edge of the tape. (The reference edge is the edge of the tape that is
nearest to the baseplate of the cartridge.)
Track 1 is the track immediately above the Directory Track. The odd numbered
tracks are positioned sequentially up from track 1. Thus, track 3 is above track 1,
and track 5 is above track 3, and so up to track 71, which is the closest to the upper
edge of the tape.
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