Dear Bombich team,
this is more about me trying to understand backing up with CCC and checksum and trying to figure out the best backup workflow for me.
I'm using CCC solely for backing up all my data, rather than creating bootable images. So I am most concerned about safety and having everything completely and truly mirrored.
I have been using CCC for incremental backups for a while now after coming from time machine, which wins for me in terms of convenience and simplicity, but lost my trust completely due to some incidents I won't go into.
The way I understand checksum is that it provides validation, that a file has been 100% copied and is exactly the same on my backup medium as on the original. I've seen it as preventing corrupt data and that CCC would warn me at the end of the process, if any and which files are corrupted or not 100% the same. The problem with checksum of course is the duration of the backup. E.g. one of my hard drives (3TB, USB 2.0) takes 37 hours to be checked by checksum. So a few people only suggest that a normal incremental backup is done first and then the same with checksum is run second. This way at least, the checksum process doesn't need to copy any files. So I have been doing this for a while, but now I thought: If a file is corrupt and I copy it with the normal process, they should be the same files on both drives. Both corrupt. And the healthy file, that used to be on the backup drive, gets thrown in the SafetyNet and will eventually be deleted. Then checksum afterwards will see the two corrupted files as 100% the same and therefore not sound the alert. But if I had run checksum in the first place, it would have said: The file is healthy on the backup drive, but corrupt on the original. Please replace the corrupt original with the backup.
Am I right with this?
So, to be safe and to prevent that I will continue to backup files that go corrupt at some point (which I experienced due to some faulty hard drives, which time machine ignored, deleted the healthy backups and overwrote them with the corrupted data), I should always run checksum only, right?
If I got anything wrong, please feel free to correct me and thank you for your time in advance.
Sincerely,
Quarter
