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macOS Sierra's Coming File System

Something that's going to be very interesting.

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LEWISTON/CUPERTINO (Rixstep) — macOS Sierra went out yesterday, with a number of features that users will cling to: Siri, iCloud Documents and Data, and the like.

One of the most interesting features of macOS Sierra is something that won't be fully ready until next year: Apple's new file system APFS.

What's interesting about this new file system isn't just the system itself, but who writes it.

From M to AP

Way back when, many years ago, in an ancient millennium no less, one SP Jobs visited the LRG lab of one AC Kay. And he was blown away. He later admitted that it wasn't until he got to NeXT that he realised what he hadn't picked up on that VIP tour, so blinded he'd been with the dazzle of Kay's 'windows'.

Apple's Macintosh vintage 1984 initially used a non-hierarchical file system with the far-fetched name Macintosh File System or MFS. What was so comical about this attempt was that the original beige box engineers had to retrofit hierarchy onto a system that wasn't hierarchical, in order to preserve the on-screen illusion that things were indeed hierarchical (when they weren't). It seems no one in Cupertino considered that Alan Kay's on-screen wizardry was a reflection of his on-disk wizardry, and not the other way around.

And so it went. MFS was fast-tracked for retirement and replaced by a true Hierarchical File System surprisingly named Hierarchical File System (or HFS). As hardware devices grew in capacity, HFS became HFS+ and several other variants.

The Finnish father of Linux has never been a big fan of Apple file systems, despite once getting a Mac tower as a gift:


Or take this gem:


'Quite frankly, HFS+ is probably the worst filesystem ever. Christ what shit it is.'

The worst part about that is he may be right. The good part is that things don't have to be like that for long.

Dominic Giampaolo has been working at Apple since 2002 - that's right: almost since the inception of OS X. What's he been doing all those years? It seems he first charged his batteries with his wife on a 'round the world' trip before returning to the west coast, but since then? APFS factors in, to be sure.

Dominic has an impressive portfolio. He's been able to tell online pundits about the internal architecture of APFS because he wrote it. Before writing APFS, he wrote Be's file system, so he's been around the block. You can see him midway in this WWDC presentation; his hair's grown out a bit in the past fifteen years since that Phileas Fogg buzzcut.


He's got some interesting links at his own site, including a 'File System Construction Kit' he seems to have built at Be. It's clean and tidy code.

Some other things Dominic's done over the years: he added journaling to HFS+, started the Spotlight project, worked on Time Machine, wrote the first version of iCloud Documents and Data, wrote another file system that never shipped, and fixed a bug at SGI to speed up the release of the movie 'Speed'. He's also been able to ferret out bugs in Intel processors. His Wikipedia page tells even more.

APFS is supposed to ship in full in 2017. This is going to be very interesting.

'I'm Dominic Giampaolo. I program computers for a living.'

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