What first looked like some CPU oddity in a monitoring graph became a full-fledged hunt for a bitcoin miner. Figuring out what happened and how they were operating is part of the investigation. Collecting evidence to make a case soon became akin to a detective story.
Data security is about preventing data from being disclosed, ensuring that only the correct people can access it. Data integrity ensures the data is correct, that it has not become corrupt due to hardware failure or other issues. With ZFS, you can get both.