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Apple File System

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Re: Apple File System

#171

I read the link and have a pretty good understanding about how computers and file systems work but can someone "explain like I'm a decently intelligent programmer" what is different about this file system? Thanks you.

This bit from 2012 by John Siracusa outlines everything “wrong” with the old file system, HFS+, and doubles as a sort of guide to what this new file system fixes.

http://arstechnica.com/apple/2011/07/mac-os-x-10-7/12/

Re: Apple File System

#172
post #60

Earlier quoted context omitted.

Presumably as with today, you'll have the option. I don't have a strong opinion on case sensitivity of file names, but I suspect they'll keep it case insensitive by default. I think for the average non-technical user that two files, "MyFile.txt" and "myfile.txt", being different could lead to some confusion, and Apple historically has apparently considered that confusion unacceptable.

Steam relies on the filesystem being insensitive.

I know Unreal Engine 4 does, but Steam does not.

Re: Apple File System

#173
post #2

Siracusa will finally be happy. ;-) Sounds an awful like like ZFS (zero-cost clones, read-only snapshots) but could it be? I would imagine they'd start from scratch to due IP issues. Clearly this is immature technology they want to get out for testing/evaluation before it's fully adopted even into their own products. (See below.) - - - from the release notes - - - As a developer preview of this technology, there are…

There is going to be some absolutely crazy sex in the Siracusa household this evening.

Re: Apple File System

#174
post #15

Just saw a comment in another thread, stating Apple had slipped in improving their Unix layer, and here comes this. New file system is not a joking matter: Microsoft failed to deliver their new FS; Linux took years to go from ext2 to ext3 to ext4, and btrfs is in forever testing; most of *BSD still use their old ones; zfs took decade to become mainstream... The information currently is very scarce on this one, but I…

Fwiw this took ten years. Apple tried to migrate to zfs and had to back off over license issues. We've been waiting since then.

Re: Apple File System

#175
post #91

Earlier quoted context omitted.

I can see why there would be conflicts going case sensitive -> case insensitive, but I can't see why there would be conflicts going the other way. Am I missing something?

I think you have it backwards. If you try to expand an archive with FOO.TXT and foo.txt, what should happen if you're writing to a case insensitive file system? $ touch HI $ touch hi $ ls HI So that's disturbing. Another problem is every software you can think of will be comparing two files case insensitively. Almost weekly I get burned by this. $ touch HI $ test -f hi && echo ok ok

That's not convincing me that I have it backwards. I was responding to this point in the parent comment:

> many case insensitive hard drives would be copied into new machines and there would be millions of conflicts

I still don't see where you get a conflict copying the contents of a case-insensitive file system to a case-sensitive one.

Re: Apple File System

#176
post #53

Earlier quoted context omitted.

Copy-on-write and snapshots are excellent building blocks for Time Machine, so much in fact that, when it was announced, I suspected it was because of ZFS (which, at the time, was being considered for OSX). It's very likely TM will be adapted to work on it (with about 20 lines of code)

I'm not sure about snapshots, TM is made to work by just copying the directory structure over, and each backup is a fully functioning hierarchy. But cloning is definitely a big deal.

Time Machine uses hard links to create a duplicate directory structure without duplicating all the files themselves; only changed files need to be copied.

As I recall, HFS+ was explicitly modified to support directory hard links, which is less common in the Unix world, explicitly to support this feature.

TM also maintains a folder called /.MobileBackups to store temporary backups while your backup drive isn't connected. OS X also maintains /.fseventsd, a log of file system operations that TM can use to perform the next incremental, instead of having to compare each file for modifications.

Re: Apple File System

#177
post #128

Earlier quoted context omitted.

ZFS needs very little memory to run. Performance is definitely better with more RAM, but the overwhelming use of memory in ZFS is for cache. Eviction is not particularly efficient due to the cache being allocated from the SLAB allocator, but that is changing later this year. Getting ZFS to run on the Apple Watch is definitely possible. I am not sure what acceptably means here. It is an ambiguous term.

The FreeBSD wiki ( https://wiki.freebsd.org/ZFSTuningGuide ) still claims: > To use ZFS, at least 1 GB of memory is recommended (for all architectures) but more is helpful as ZFS needs lots of memory. Is that inaccurate?

because it has its own FS cache.

Re: Apple File System

#178

I read the link and have a pretty good understanding about how computers and file systems work but can someone "explain like I'm a decently intelligent programmer" what is different about this file system? Thanks you.

It's apple reinventing the zfs and btrfs wheels. Which are already mature, useable and open source. Google them and see what they do well, and you might get some ideas.

Both filesystems have copyleft licenses so that may factor into Apples decision.

Re: Apple File System

#179

> Flash / SSD Optimization I.e., a "unique copy-on-write design" > Space Sharing Basically, ZFS datasets. > Snapshots If those can be sent: Finally Time Machine done right. > The AFP protocol is deprecated and cannot be used to share APFS formatted volumes. Interesting. > An open source implementation is not available at this time. Apple plans to document and publish the APFS volume format when Apple File System is r…

What will happen to Spotlight search on network shares? At the moment, they are based on AFP.

Re: Apple File System

#180

> Flash / SSD Optimization I.e., a "unique copy-on-write design" > Space Sharing Basically, ZFS datasets. > Snapshots If those can be sent: Finally Time Machine done right. > The AFP protocol is deprecated and cannot be used to share APFS formatted volumes. Interesting. > An open source implementation is not available at this time. Apple plans to document and publish the APFS volume format when Apple File System is r…

What will happen to Spotlight search on network shares? At the moment, they are based on AFP.
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