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Comment by ahl | Hacker News Reader

Talking to the Apple engineers it really didn't seem to be an issue of computation. They seemed genuine in their belief that they could solve data integrity with device qualification. While I asked them 100 questions they asked me 2: had I ever actually seen bit rot (yes), and what kind of drives did we ship with the ZFS Storage Appliance (mostly 7200 nearline drives).

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That's dumbfounding. I know first hand a certain monthly-fee movie streaming service and the CDN I work for can tell anyone who wants to hear about handling silent corruption and bit rot and we have a relatively small fleets. At home ZFS saved me from a faulty power supply on my old workstation.

And.. the red herring here is, Apple users will want to plug in third party storage. There's just no way to contain what someone will plug in to USB and ThunderBolt, and it's insane to think APFS would not be ready to help there.

That would suggest that APFS is only relevant for internal storage procured by Apple. Do they not intend for it to be used on external storage?

They mentioned that it would be used on removable media as well.

If the crypto layer has proper MACs then presumably checksums at lower layers aren't so important. Did they give you much indication that they thought disk encryption would become standard?

I've had an Intel S3500 brick within 4 weeks and a SanDisk Extreme Pro start to show occasional I/O errors after a few months. The latter doesn't just lead to bit rot, but unreadable files. With ZFS I was able to identify those with a quick zpool scrub. Which shows how valuable checksumming is even in the absence of ECC memory. At least according to my anecdotal experience, flash is much more flakey than conventional hard disks, so the assumption that stuff just doesn't happen seems ludicrous.

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