When Windows users suddenly discover that their files have vanished from their desktops after interacting with OneDrive, the issue often stems from how Microsoft’s cloud service integrates with the operating system. The automatic, near-invisible shift to cloud-based storage has triggered strong reactions from users who find the feature unintuitive and, in some cases, destructive to their local files.
Notifications will go a long way toward helping with that. Check all assumptions, check all exit codes, notify and stop if anything is amiss. I also have my backup script notify on success, with the time it took to back up and the size and delta size (versus the previous backup) of the resulting backup. 99% of errors get caught by the checks and I get a failure notification. But just in case something silently goes wrong, the size of the backup (too big or too small) is another obvious indicator that something went wrong.
I know. I just had become lazy enough to take the daily notification’s subject line (“backup4l has run successfully”) as evidence that everything was OK. If I had looked inside the bloody mail I’d have notices that the backup’s size was 0B all the time because my self-rolled XZ-compression script failed to add data to the archives it “successfully” created. That’s what I meant with “re-testing” - I should better have written “re-validate”. My unforgiveable fault was not to look directly at the generated archives after changing the compression from bz2 to xz. Which was pretty pointless anyway as it turned out.