Reader ST discovered that aging data backup CDs he had burned had become unreadable, so now he uses QuickPar to make recovering data on disc with bad sectors possible. Here's how he does it.
I have some discs burnt years ago and recently I found them not 100% readable. I'm buying more reliable discs now but I realise even with better media as times goes by the data will become more precious and inevitably...damaged (due to the physics nature of optical media). So from now on when I compose a disc to nearly full, instead of wasting the spare space I use freeware QuickPar to generate recovery volumes and burn them together.
As Usenet mavens know, QuickPar creates "parity volumes" which can verify and recover information for a file or a group of files. If some files are damaged or missing but the needed information is contained in the parity volume, QuickPar may be able to reconstruct the originals from the damaged files and the PAR volumes.
ST explains how to use QuickPar.
Drag the about-to-burn files to QuickPar, adjust the redundancy level so the "recovery data size" matches the spare space on disc (I always drag files to the burning tool first to see how much space left), then press Create.
After a while it will generate bunch of files with extension .PAR2.
Then drag them to the burning tool. Together with original files they should fit on one disc perfectly.
From there, you're good to go burn your disc. Then, in case you need recovery, your PAR files will come in handy. ST continues:
One day when "bad sectors" occur I'll use the free IsoBuster (or any other bad disc saver like Badcopy) to extract the most from my disc, with of course some files missing and some files partially missing.
I only hope not all PAR2 files are missing. Then here comes QuickPar again: double click on any .PAR2 file, the QuickPar will open and start to scan every file it finds, hopefully and very likely (if the disc is not heavily damaged), it will repair your precious data!
Tip 1: QuickPar only accepts files but not folders. But here's a small hack: open windows search and search * in your desired folder then drag the result files to QuickPar
Tip 2: You can choose to only protect VIF (Very Important Files) instead of the whole disc with QuickPar
Tip 3: This method is Windows only, but the idea is universal so I believe Linux users have better solutions.
Tip 4: This is very useful when you back up a lot of movies.