When I started using a NAS, I spent the first couple of years in a false sense of security, believing that redundant drives meant my data was safe. The problem is that RAID (or RAIDZ, if you’re running ZFS like I am) protects you from a drive failure, and that’s about it. It doesn’t help if you overwrite the wrong file or delete something you meant to keep. The redundancy just means that your mistake is synchronized across all the hard drives in the pool.