Archiving error correction files

dvdisaster Version 0.72.6 / 0.79 (devel-3) | To the Internet version

Contents
News
Overview
Howtos
· | The big picture
· | Scanning media for errors
· | Putting error correction data on a separate file
| - | Decision help
| - | Basic settings for reading
| - | Creating the error correction file
| - | Archiving error correction files
| - | Advanced settings
· | Putting error correction data on the medium
· | Recovering media images
· | Getting information about images and error correction data
· | Testing image compatibility
· | Dialogs and buttons
Download
Questions and Answers
Bug reporting
Creating error correction files |
Archival
### Tips for archival of error correction files CD/DVD/BD are currently among the most cost-effective exchangeable mass storage media. Therefore you are probably considering them for storing error correction files. Nothing is wrong with doing so, but be aware that your data and protective error correction files are kept on media with equal reliability. When you encounter read errors on a data medium it is likely that the medium containing the respective error correction files has also gone defective. After all both media have been written at the same time, and they have the same aging characteristics.
|  | This might come at a surprise, but it can not be guaranteed that an error correction file remains usable when it is stored on a defective medium - here is a explanation of the technical background.
Therefore it is important to protect error correction files just as if they were normal data. To be more specific, the medium containing error correction files must be protected with error correction data as well. Here are two ways of doing this: Storing error correction files on separate media: Use additional media just for keeping the error correction files. If you use no more than 80% per medium for error correction files it can be augmented with error correction data. This allows you to recover the medium if you run into problems reading the error correction files at a later time. Storing error correction files on the next medium in sequence: Maybe you are using media for an incremental backup strategy. In that case you could collect files until the first medium can be filled. Write that medium as usual and create an error correction file for it. Include that error correction file into the backup set which will go onto the second medium. When the second medium has been written, write the error correction file for it onto the third medium and so on. This way all media in the chain are protected with error correction files (with the ecc file for the last medium residing on hard disk until another medium is written). Of course Murphys Law may strike and result in all media of the chain becoming defective. In that case you need to recover all media, starting with the most recent one ;-)

Copyright 2004-2014 Carsten Gnörlich. Verbatim copying and distribution of this entire article is permitted in any medium, provided this notice is preserved.