Quantum TC-L53FN-AR Guia do Utilizador descarregar pdf (Página 53)

Chapter 4 Theory

Data Buffer

LTO-5 Tape Drive User’s Guide 39

• 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

In its default configuration, the LTO-5 Tape Drive has a 256-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.

Data Integrity

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-5 Tape Drive is less than 1 hard error in 10

bits. The undetectable error rate is 1 in 10

bits read.

Error-correction Code

(ECC)

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.

There are two levels of Error Correction Coding (ECC). These two levels

are orthogonal — that is, an ECC codeword at one level intersects ECC

codewords at the other level just once, which means there will be only

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