Checking a disc

Why

Discs age over time. The check reads every file on the disc and compares it with its checksum. It also checks the Sigelith seal and the file proofs. If the disc is starting to fail, you find out while the files can still be read or repaired.

Before you start

• Check a disc every two years. The program reminds you by itself:
  • in the “Archive discs” window it shows the line “Time to check these discs (every two years)” with the disc labels;
  • overdue dates in the “Next check” column are in bold;
  • at most once a week it shows a Windows notification.
• Also check a disc after recording it with another program (for example from an ISO image) and whenever you are unsure whether it is intact.
• The check changes nothing on the disc.

Step by step

1. Insert the disc in the drive.
2. In the menu on the left click “Restore”, at the bottom of the page “Archive discs…”, and then “Check disc…”.
3. In the “Disc:” box, choose the disc from the drive and click “OK”.
4. An encrypted disc: the program asks for the disc password. Without the password it checks that the files on the disc are intact. With the password it also checks that their content matches the seal. Checking with the password is recommended.
5. Wait until the program has read the whole disc. For a 25 GB disc this can take several tens of minutes.

What you should see

“Disc … is intact: all files match their checksums” with the number of files. The result goes into the register, and the date of the next check moves forward by two years.

If the disc was recorded before the seal was complete, the program adds that the Sigelith confirmation on the disc does not have the week's signature yet. This is not a fault of the disc: the full time proof is given by the page named in the README on the disc.

What next

• The disc is intact: put it back in its place.
• The disc has problems: see below.

If something goes wrong

• “Disc … has problems” and a list of files (“changed”, “missing”, “unreadable or damaged”): the disc is starting to fail or has been changed.
  • If you have these files in the backup on the drive, record a new disc (see “Recording a backup version on a disc”).
  • If not, repair the files with the recovery data on the disc and record them on a new disc (see “Reading a disc without the program”, the “Repairing damaged files” part).
• “This disc is not in the register. Add it…?”: the disc comes from another computer, or the register was lost. Click “Yes”. The program adds this disc and the earlier discs recorded in its “catalog” folder.
• “This is not a Sigelith Backup archive disc”: there is another disc in the drive.
• The check takes too long: you can stop it with the “Stop” button. The disc is left untouched, and the result does not go into the register.