Dds-Dc Recording Format - Seagate STD124000N Product Manual

Chapter 1

DDS-DC Recording Format

Page 8
A superset of the basic DDS format, DDS-DC drives can write compressed and
uncompressed data to the same cartridge. Because DDS-DC is based on the DDS
format, backward-compatibility is maintained.
Introduced by the DDS Manufacturers Group and approved by ANSI and ECMA,
DDS-DC is a record compression industry-standard format that provides support for
lossless compression algorithms based on substitution—such as those of the
Lempel-Ziv family.
This format supports compressed and uncompressed records. A recorded DDS
cartridge may contain compressed records, uncompressed records, filemarks and
setmarks. Compressed records exist within recorded objects called entities . Entities
and uncompressed records are collected into groups.
Many aspects of the DDS-DC format are identical to those of the DDS format:
z
The series of transformations (randomizing, interleaving, generation and
inclusion of two Reed-Solomon error-correction codes) applied to a group
before recording
z
The tape layout
z
The third group-based level of Reed-Solomon error-correction codes (C3)
The only differences between the DDS and DDS-DC formats are in the contents of
the groups.
Introduction
DAT Drives