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4 Theory
This chapter describes operational theories used in the LTO-2 half-height drive.
The topics covered in this chapter are:
•
“Track Layout” on page 30
•
“Recording Method” on page 31
•
“Data Buffer” on page 31
•
“Data Integrity” on page 31
•
“Data Compression” on page 33
Track Layout
With the LTO-2 half-height drive, there are 512 data tracks on the LTO tape, numbered 0 through
511. Data track 511 is the track closest to the bottom edge of the tape (the reference edge). The
area between adjacent servo bands is a data band. There are 4 data bands, each of which
includes 128 data tracks. The data bands are numbered 2,0,1,3. Data band 2 is closest to the bot-
tom edge of the tape.
A track group is a set of tracks that is recorded concurrently. The sets of 16 data tracks in a data
band are data sub bands. There are 8 data sub bands per data band. The data tracks are accessed
in a serpentine manner.
A wrap is a track group recorded in the physical forward or physical reverse direction. The wraps
are recorded in a serpentine fashion starting in data band 0. The tape contains 64 track groups, 32
written in the forward direction and 32 written in the reverse direction. Even-numbered wraps are
recorded in the forward direction (BOT to EOT), and odd-numbered wraps are recorded in the
reverse direction (EOT to BOT).
Figure 10 on page 31 shows the layout of data on an LTO tape.
