CD Data Extraction

Data CDs can contain almost any computer file: documents, photographs, databases, audio files, video files, installers and legacy software. Extraction must preserve the directory structure and file contents accurately.

CD-ROM and data discs

A data CD should not automatically be treated like an audio CD. The National Archives notes that a Data CD may contain anything from small MP3 files to larger uncompressed Broadcast WAVE files.

Preserving folders and filenames

Begin by identifying the disc format and examining its directory structure without altering the source. Record the volume label, filesystem information and visible contents.

Legacy file systems

For routine access, files can be extracted into a controlled folder structure. Where the disc contains unusual software, legacy structures or important metadata, a complete disc image may be more appropriate.

Extraction versus disc imaging

Preserving original filenames, folders, timestamps where available and associated metadata can be important for future interpretation.

Checksums and verification

After extraction, compare file counts and sizes and calculate checksums. Where a source is damaged, record which files or sectors could not be recovered.

Reference guidance: This article is informed by optical-media preservation guidance from the U.S. National Archives and the Library of Congress Recommended Formats Statement. Where appropriate, the article distinguishes preservation guidance from practical extraction procedures.