Quantum LTO-2 User Manual

Chapter 4  Theory

Recording Method

LTO-2 Half-Height Tape Drive User’s Guide

29

Recording Method

4

The LTO-2 Half-Height Tape Drive records data using write-equalized 

(1,7) Run Length Limited (RLL) code. RLL (1,7) Data bits are defined as 

follows:
• A 

 is represented by a flux transition at the center of a bit-cell.

• A 

 is represented by no flux transition in the bit-cell.

Data Buffer

4

In their default configuration, the LTO-2 Half-Height Tape Drive has a 

32-Mbyte buffer. The buffer controller has a burst transfer rate of 320 

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.
The error rate of the LTO-2 Half-Height 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.

4

The use of Cyclic Redundancy Checking (CRC), two-level orthogonal 

Error Correction Coding (ECC) provides a very low probability of 

encountering a hard error. During the read process, ECC correction is 

performed on the fly without affecting tape streaming.