The useful answer to “How long will this disc last?” is a preservation plan: read it while you still have a compatible drive, copy the contents, verify the copy, and keep independent copies you can check again. A disc's age or an archival label cannot tell you how much readable life remains in that particular disc.
This guide is for your own photos, documents, recordings, and other files on CDs and DVDs. Start with a working computer, a drive that supports the disc format, and enough free storage for the contents plus another copy. Work on one disc at a time so errors and filenames remain traceable.
Identify the disc and the content
The 2003 NIST/CLIR guide to optical-disc care describes different recording layers: pressed ROM discs, write-once recordable discs, and rewritable media. Their aging mechanisms and recording histories differ. Storage conditions, manufacturing quality, and handling also affect readability. A broad lifespan estimate is a population-level expectation under assumptions, not an expiration date for a family album.
On a narrow screen, scroll the table sideways. Keyboard: focus the table and use the arrow keys.
| What you have | First useful action | What to preserve |
|---|---|---|
| Data CD or DVD showing folders | Copy the complete folder tree to a new, empty destination | Original filenames, files, subfolders, and a note identifying the disc |
| Audio CD showing track shortcuts | Use an audio extraction application with error reporting | Extracted audio, track order, titles, and the extraction log; copying shortcuts does not extract the recording |
| Home-authored video DVD | Identify the disc structure and use software that understands it | The complete video structure or a suitable disc image, plus a convenient viewing copy if needed |
| Old backup set or application-specific archive | Identify the creating software and all volumes | Original archive files and documentation, plus restored files after a successful restore test |
An image of a disc preserves a representation of its structure; extracted files are easier to browse. Choose a tool and image format appropriate to the medium, especially for audio and multisession discs. This guide's comparison download checks ordinary file trees; it does not extract audio, repair sectors, or validate every kind of disc image.
Make a disc inventory before copying
Give each disc an identifier such as DISC-001, written on its case or inventory sheet. Record its label, approximate recording date, contents, known duplicate locations, and any visible damage. Prioritize irreplaceable material with a single remaining copy, discs showing read trouble, and formats for which you have only one working reader.
Create a folder such as Disc-preservation/DISC-001/original-files. Keep notes and verification reports alongside that folder, outside the files being compared. For an old backup, record the software name and version printed on the disc or packaging before trying to interpret the files.
Download the disc preservation kit, containing a plain-text inventory template, instructions, and a small Python file-comparison tool. The kit also works as a checklist without Python.
Copy first, then prove what arrived
- Inspect the disc for cracking or loose labels before putting it in a drive. Set damaged discs aside for appropriate recovery advice. For an intact dirty disc, follow the care guidance below.
- Open a data disc in the file manager. Copy its entire contents into the empty
original-filesfolder. Avoid renaming or reorganizing the first preserved copy. - Record any skipped files or read errors. A completed progress bar with a skipped-file message is an incomplete copy.
- Compare source and destination relative filenames and sizes. Then compare file hashes where the disc remains readable. A hash is a fingerprint calculated from file bytes; matching SHA-256 values provide strong evidence that two reads produced identical bytes.
- Open representative photos and documents and play recordings at several points. Byte agreement checks transfer integrity; opening the files checks whether your current software can interpret them.
The kit requires Python 3.10 or later. Extract it, open a terminal in the extracted folder, and replace the example paths with yours:
python verify_files.py "D:/" "C:/Disc-preservation/DISC-001/original-files" --report "C:/Disc-preservation/DISC-001/verification.json"
The tool reads both folders without changing their contents. It reports missing, extra, mismatched, and unreadable files; it refuses overlapping folders and symbolic links. Exit code 0 means every listed file matched and the source was nonempty. A nonzero result needs investigation. Its hashes use Python's documented hashlib implementation.
For a fragile disc, repeated reading may stall. Save what you can, retain the error log, and consider a recovery workflow that records unreadable sectors or professional help for important material. Do not describe a partial extraction as verified simply because its recovered files open.
A worked preservation record
Suppose a fictional DISC-001 contains 420 photographs. The first copy reports 418 copied and two read errors. Mark the disc partial: two missing files, even if the 418 recovered photos pass comparison. Keep the filenames of the missing items so a later attempt can target them.
After a second compatible drive reads the remaining files, compare the complete destination again. Record the drive used, date, 420 matching files, and results of opening sample images. Copy that folder and its notes to another storage device. Compare the second copy against the first verified copy to avoid another full read of the disc.
Store discs and maintain the files
Handle discs by their edges or center hole. Keep them in protective cases, upright, away from sunlight, heat, dampness, and abrupt environmental changes. For ordinary surface dirt, the NIST/CLIR guide recommends gentle straight strokes from the center outward with a clean, soft cloth. Avoid abrasive polishing experiments and circular scrubbing on important originals. Follow media-specific guidance for stubborn contamination.
The Library of Congress photo-preservation guidance recommends copies in different places and at least annual readability checks. Put a reminder in your own calendar to open files, check the copies, and replace failing or becoming-obsolete storage. Keep one copy separate from everyday editing and automatic synchronization, which can also propagate deletions.
Preserve original files when making smaller viewing copies or converting an old format. Record which software performed the conversion and inspect the result. Once a file is preserved, the next recurring task is maintaining access to it; the physical disc becomes one part of that history.