Quantum Tape Drive LTO-3 - Manual (Page 47)

Chapter 4 Theory
Recording Method
LTO-3 Tape Drive User’s Guide 33
Recording Method
4
The LTO-3 Tape Drive records data using write-equalized (0,13/11) Run
Length Limited (RLL) code. RLL (0,13/11) Data bits are defined as
follows:
•
ONE
is represented by a flux transition at the center of a bit-cell.
•
ZERO
is represented by no flux transition in the bit-cell.
Data Buffer
4
In its default configuration, the LTO-3 Tape Drive has a 128-Mbyte buffer.
The buffer controller has a burst transfer rate of 320 Mbytes/sec, and
utilizes bank switching to achieve a maximum average bandwidth of
nearly 240 Mbytes/sec. The high bandwidth is needed to support look-
aside data compression in the case of compressible data being transferred
from SCSI at 160 Mbytes/sec.
Data Integrity
4
The mechanical and electrical design of the drives ensures that drive
performance does not degrade over a drive’s operating life. Changes in
head alignment, head wear, component drift, and other factors are
minimized to ensure that data integrity and interchange capability are
not compromised over the drive's operating life. In addition, the drive
incorporates adaptive FIR filters that are capable of modifying the
equalization of each read channel dynamically to compensate for many of
those changes.
The error rate of the LTO-3 Tape Drive is less than 1 hard error in 10
17
bits. The drive’s undetectable error rate is 1 in 10 27 bits read.