ahl

Good catch; thanks.

Yep! They paid me the usual fractional pittance offered to authors.

edit: and to be clear I'm delighted and flattered to see my work featured in Ars!

The failure mode of hardware is not all or nothing. A single sector in an HDD or a single page in an SSD can fail and the rest can be fine for years; both HDDs and SSDs have many spares for this expected condition.

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).

Unclear, but a member of the ZFS development team at Apple told me that Giampaolo complained that ZFS would never work on the phone. So the team demonstrated it working on the phone. I know of no obstacles to making it work on the watch other than engineering.

This guy (i.e. me) wasn't aware of this functionality in btrfs. Are reflinks commonly used? Yes, I know more about ZFS than the other filesystems mentioned.

Fair enough; and right now cp doesn't use the fast clone functionality, but it assuredly will. I'm not sure 'cat <file >file.dup' is reasonable for most users.

Apple started in 2006 with no deal or coordination with Sun. Later when the FUD started, they were looking for protection from patent lawsuits (i.e. from NetApp), for support and expertise, and, possibly, reassurances around patent clauses within the CDDL with which I'm not an expert.

100% true about the performance cliff, though at Delphix we worked a bunch to raise performance before the cliff and to push out that cliff. All COW filesystems filesystems (and I'll throw SSD FTLs into there as well) require over-provisioning for consistent performance.

And it's also a fair point that for enterprise storage running at 80%-90% of capacity is a reasonable restriction whereas the drive on my laptop is always basically %99 full. It will be interesting to see how APFS addresses this since I'd guess that most of their users look more like my laptop than my file server.

Hard links to directories are weird enough that many modern filesystems (including APFS) don't support them. Yes the language is perhaps unnecessarily colorful; just trying to keep things interesting.

Definitely not. ZFS was primarily focused on spinning disks. Take for example the fact that the project discarded block indirection early on: the resulting random reads would be basically fine on SSDs and debilitating on HDDs. Ditto TRIM which is still not (IMO) fully baked in ZFS.

Agreed with all of this, but it's hard to imagine the licensing was truly insurmountable.

It would be a strange kind of NIH that excluded ZFS but welcomed HAMMER...

The Sun acquisition was announced in 2009 and closed in 2010. It may have been related, but I have my own suspicions about about what caused Apple to jettison their port.

The spartan description of APFS certainly sounds like the (partial) feature list for ZFS--the comparisons made in the comments here are on-point. ZFS though took around 5 years to ship and, arguably, another 5-10 to get right. I say this having shipped multiple products based on ZFS, writing code in ZFS, and diagnosing production problems with it.

On-disk consistency ("crash protection"), snapshots, encryption, and transactional interfaces ("atomic safe-save") will no doubt be incredibly valuable. I don't think though though that APFS will dramatically improve upon the time it took ZFS to mature from a first product to world-class storage.

Some commenters have opined that (despite Apple distributing ZFS for Mac OS X at WWDC nearly a decade ago) that ZFS would never be appropriate for the desktop, phone, or watch. True ZFS was designed for servers and storage servers, but I don't think there's anything that makes it innately untenable in those environments--even its default, but not essential, use of lots of RAM.

Who knows... maybe Apple have spent the decade since killing their internal ZFS port taking this new filesystem though the paces. Its level of completeness though would suggest otherwise.