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Apple File System

developer.apple.com

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Re: Apple File System

#181

Post by jug »

lewisl9029 wrote: post #47
xd1936 wrote: post #16

Earlier quoted context omitted.

Sure, this is a developer preview. Final release in 2017 will surely make this FS the default.

That's what people were hoping for with ReFS from Microsoft, which released years ago, but that still hasn't happened yet.

OTOH Microsoft has a terrible track record of overpromising and underdelivering their next gen file system. I give Apple the benefit of doubt here. It is worded so that the limitations for the better part clearly sounds related to this being a preview release.

Re: Apple File System

#182

Post by drewda »

whorleater wrote: post #66
lewisl9029 wrote: post #47

Earlier quoted context omitted.

That's what people were hoping for with ReFS from Microsoft, which released years ago, but that still hasn't happened yet.

Apple is far more willing to switch to more newer technologies than Microsoft is.

... and Microsoft is far more willing than Apple to put effort into backwards compatibility.

Re: Apple File System

#183

Post by prutschman »

cjensen wrote: post #167
skrause wrote: post #19

No checksumming?

Checksumming makes no sense on modern hardware. Hard Drives and SSDs use CRCs already. When a sector goes bad on a hard drive, the firmware will mess about retrying and altering the analog amplifiers to try to get the signal back. If it gets the data back, it might "recover" by moving the data to spare sectors. Without a CRC, the firmware would have no way of differentiating between a sector read correctly and one th…

Checksumming makes sense when the checksum accompanies a pointer to another block. i.e. a directory entry says subdirectory contents are found in block 1027 /with checksum 0xdeadbeef/.

If block 1027 is errantly overwritten due to a bug in the filesystem, the block driver, the DMA subsystem, or the device firmware, the FS will know as soon as it goes to fetch block 1027 that something went wrong. This is true even if the block is still internally consistent; perhaps the write was misdirected, another sector was incorrectly read, or a failure in the flash translation layer caused a newer write to be lost.

If there's any redundancy to the system, whether storing the metadata in multiple places on the disk, or on different disks in an array, the FS can then check all the others and, crucially, detect which version is correct.

Re: Apple File System

#186

Post by whorleater »

drewda wrote: post #182
whorleater wrote: post #66

Earlier quoted context omitted.

Apple is far more willing to switch to more newer technologies than Microsoft is.

... and Microsoft is far more willing than Apple to put effort into backwards compatibility.

I'm not saying Microsoft's approach is bad, just pointing out that there's a much higher chance of rapid adoption for this new filesystem.

Re: Apple File System

#187

Post by mioelnir »

kstrauser wrote: post #150
ryao wrote: 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?

I've ran the initial FreeBSD patchsets for ZFS support on a dual-p3 with 1.5g ram, so 1g for a recent version should be more than doable. ZFS on FreeBSD has become a lot better with low-memory situations.

There are two additional things to consider.

ZFS uses RAM mostly for aggressive caching to cover over both spinning disks and the iops tradeoff vdevs make over traditional raid arrays. Thus low memory is not such a big deal if you have a pool with a single SSD or NVMe device.

The other point to consider is that on at least any non-Solaris derived platforms, the VFS layer does not speak ARC. So data is copied from an ARC object into a VFS object, taking up space in both. If you are able to adopt your platform to use the ARC as direct VFS cache, you can save RAM that way as well.

Re: Apple File System

#188

Post by lewisl9029 »

bjt wrote: post #91
crucialfelix wrote: post #81

Earlier quoted context omitted.

More problematic is that many case insensitive hard drives would be copied into new machines and there would be millions of conflicts. Some utility would have to sit there and annoy people by asking them to make decisions.

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 the parent meant the other way around too.

However, the transition between the case insensitive and case sensitive filesystems isn't going to happen overnight. People will be copying files around both ways for quite some time, so the insensitive -> sensitive case is still going to be a concern.

Re: Apple File System

#189

Post by watersb »

ahl wrote: post #161

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 t…

Yes. I was a heavy user of ZFS on Mac OS X back then. Was on the developer mailing list for that implentation, submitting bugs and talking to Apple developers working like mad to ship it.

Then Steve Jobs' buddy Larry bought Sun, and licensing of ZFS became basically impossible to sort out on time. So they dropped it.

Was that 2007 or 2009?

Re: Apple File System

#190

Post by lewisl9029 »

jasonjei wrote: post #8
mailslot wrote: post #3

Another proprietary filesystem? I was really hoping they'd adopt ZFS fully.

Apple says they intend to open-source the file system in the docs. Open Source : "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 released in 2017."

Would it be wishful thinking to hope Microsoft would follow suit by open sourcing ReFS?
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