The ‘ddrescue’ is still running (current ETA: 2.5 more days), and there’s some good news in that it’s stopped logging errors and so far there’s only around 60MB worth of missing data out of 4TB. I’ve also received a couple of 8TB external drives so I have some spare room now to start parts of the recovery process, like getting data out of the ‘dar’ backups.
Fortunately, test runs on the backup drive show that the backups are not affected by the bad block I found on that drive. Unfortunately, I also realized that since the backup was in progress when the drive failed, I’m not sure if maybe that backup run picked up and stored some corrupted data as it was running.
So, I have the following data to work with:
- A fully-intact base backup that dates from July 2017.
- The partial, might-possibly-have-some-corruption differential backup from just before the failure.
- The data salvaged from the failing drive.
My plan so far is that once the ‘ddrescue’ is done, I take the bad blocks list and run e2fsck against the salvaged data. This should get me a list of files that were hit by the bad blocks and could not be recovered. For each of those files (hopefully the list isn’t too long!), try and find a copy in the base backup. If it’s not in the base backup, or I really need a newer version than that one, get it from the differential backup and try and eyeball it for corruption. If any of the ripped DVDs gets hit (quite likely, they took up a lot of the space), note which one and get ready to re-rip it.
Too bad this is all going to happen at USB2 speeds though…