Tens of millions of users have been using HFS for decades mostly with zero issues. I personally have used a Mac since the Mac+ and not one had corruption due to the filesystem. I would describe it as battle hardened for sure.
“mostly with zero issues” is the same as saying “with issues”.
I would generally agree that it's rare for e.g. HFS to corrupt its own metadata due to bugs but bit-rot happens. If you think you haven't encountered it, you probably haven't actually checked your files closely enough – this is particularly easy to miss with things like video or image formats which were designed to tolerate a few bit-flips.
The reason why so many Mac users were interested in ZFS was that a modern filesystem incorporates strong integrity checks so you are guaranteed to either read back the bytes you originally wrote or get an error. That's a much better way to work than requiring you to use a tool which does strong hashes periodically to see if anything has broken.
Something like ZFS would be a double edge sword for Apple.
A lot of consumers are quite obvlious to bit rot. As you point out - most of this occurs in large media files which they are unlikely to notice. Even with things like corrupted documents they will likely blame it on an application glitch.
With ZFS they will see scary diagnostic messages. Consumers will want their SSD or RAM replaced. (ZFS does a great job of catching RAM errors on systems without ECC)
This would no doubt drive higher warranty costs for Apple and cause consumer dissatisfaction.
> This would no doubt drive higher warranty costs for Apple and cause consumer dissatisfaction.
I'm skeptical that a proactive warning would be more dissatisfying than just finding it out years later, when other copies are harder to locate. In particular, I'd be surprised if a hypothetical feature like this wouldn't be integrated with their other services: “A local failure was detected and replaced with a pristine copy from iCloud”
The other really interesting question would be whether they'd ever consider something like the ZFS copies feature to directly trade maximum disk capacity for redundancy. That'd be much easier to implement for Apple since they control so much of the platform and the largest files which most people have tend to be things which are provably known to be local copies of something which can be re-downloaded, so the total cost of doubling storage for unique local files might be worth the peace of mind for many users.
> This would no doubt drive higher warranty costs for Apple and cause consumer dissatisfaction.
I suspect the decision not to use ZFS was (assuming it wasn't simply spite at Sun pre-empting Jobs' announcement) that it would cause dissatisfaction, but from a different direction: ZFS was designed for Sun's customers: companies employing dedicated sysadmins. ZFS was incredibly unfriendly back when Apple would have been evaluating it. User experiences like "you filled up your filesystem? Oh well, you'll have to reformat and restore from backup." may be acceptable in an enterprisey setting, but aren't going to cut it with the iMac crowd.
