Recording Method; Data Buffer; Data Integrity - Quantum LTO 4 User Manual

Recording Method

Data Buffer

Data Integrity

LTO-4 Half-Height Tape Drive User's Guide
The LTO-4 Half-Height 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:
• is represented by a flux transition at the center of a bit-cell.
ONE
• is represented by no flux transition in the bit-cell.
ZERO
In its default configuration, the LTO-4 Half-Height 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 the SCSI.
The mechanical and electrical design of the drive ensures that drive
performance does not degrade over time. Changes in head alignment,
head wear, component drift, and other factors are minimized to ensure
that data integrity and interchange capability are not compromised. The
drive also incorporates adaptive Finite Impulse Response (FIR) filters that
modify the equalization of each read channel dynamically to compensate
for many of those changes.
The error rate of the LTO-4 Half-Height Tape Drive is less than 1 hard
17
error in 10 bits. The undetectable error rate is 1 in 10
Chapter 4 Theory
Recording Method
27
bits read.
25