Backups and Corruption
This article was originally a war story about data corruption and the backup system that failed me. It was intended to serve three purposes:
- to document the backup system that I ended up using;
- to document the reasoning behind the design of the system; and
- to find out if anyone else had experienced data corruption due to a macOS update.
As gerikson said, I kind of buried the lede. No-one else seemed to pick up on the fact that a security update from Apple corrupted user files. Everyone else was keen to describe their own backup systems or to miss the point about checksums. To be fair, I did get some helpful advice on how to improve my backups... but I never did find out whether anyone else has experienced data corruption after a macOS update.
Since then, while perusing old Time Machine backups for an entirely different reason, I found a few corrupted files from before the macOS update. This disproves the hypothesis that the OS update was directly responsible for corrupting my data. It is odd that the vast majority of the corruption coincided with the update but clearly the update alone cannot be to blame. Perhaps there was some hardware problem that was somehow exacerbated by the update process. Either way, I don't have enough evidence to investigate this further.
Since I no longer use the iMac or the backup system, this page no longer serves any real purpose. It now exists solely to avoid breaking the rules.