How to check a burned disc matches the original

Open Tools > Verify a disc in Burn by Zaweba and choose what to compare the disc with: the ISO image it came from, or the folder it was made from. Burn reads the disc and checks it against the original, so you know whether the burn is a true copy. Discs burned in Burn can also be checked automatically straight after burning.

A disc that looks fine in Explorer can still have a file that won't read. Checking catches that while you still have the original to burn again from.

Checking straight after burning

The simplest way is not to need a separate step at all. Burn's setting Check every disc after burning reads every file back after each burn and compares it with the original. It's recommended and takes a few minutes more. For audio CDs, the track list and each track's sound are checked instead.

Backups go further. The Backup Assistant takes a SHA-256 fingerprint of every file before burning, then reads every file on every disc back and compares it, listing each file as passed or failed. A disc that fails can be burned again.

Checking a disc later

Verify a disc is for discs you already have. Maybe it was burned by another program, or before you turned checking on, or you want to know whether an old disc still reads properly. Put the disc in, open Tools > Verify a disc and point Burn at the original.

Compare against an ISO when the disc was burned from an image. Compare against the folder when the disc was made from files on your PC. Either way, Burn reports whether the disc matches.

Keeping something to compare against

A check needs an original. When Burn makes an image with Create image from folder or Read disc to image, it records a SHA-256 checksum, so you can later tell whether the image itself is still intact. Keeping the ISO of an important disc, and its checksum, means you can verify that disc or make a new one at any time.

For backups, the fingerprints are kept with the backup and used again at restore time, so every file that comes back is checked too.

Old discs are worth checking now and then too. Discs age, especially if they've been kept somewhere warm or in sunlight, and a disc that read perfectly five years ago may not today. A yearly check of important discs against their ISO or source folder tells you while there's still time to make a fresh copy.

When a disc doesn't match

Burn the disc again on a fresh blank. If failures keep happening, check the blanks, try a slower write speed, and look at Tools > Drive information to see what your drive supports and whether buffer-underrun protection is available. An old disc that no longer matches is a sign to copy its contents somewhere safe while you still can.

Checking costs minutes. Finding out years later that a disc never burned properly costs far more.