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Apple File System

developer.apple.com

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201–210 of 406 posts

Re: Apple File System

#201

Post by mioelnir »

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…

SSDs use CRC to deliver their probabilistic data storage approximation. FS level checksums are, among others, for when that fails.

FS level checksums also cover bitflips on your bus during the write phase (the drive will crc the already bad data) or during the read phase (you receive different data than your drive sent).

Re: Apple File System

#202

Post by watersb »

lai wrote: post #184

Oh I forgot, you can't read Apple documentation on a mobile chrome browser.

Last week, Apple modified their formatting for the User Support Forums, so I can actually see readable text on an iOS device.

That only took... a very very long time.

(Wonder if Radar has a new look...)

Re: Apple File System

#203

Post by zingplex »

matthewmacleod wrote: post #149
qmr wrote: post #130

Earlier quoted context omitted.

Not sure why you're being downvoted. Too many fanboys I guess. I would hope the community is more enlightened than that.

Because it's just kind of lazy and incorrect, that's why. Apple did promise to open FaceTime, and was promptly sued – that's why it's not open. AFAIK there was no promise to open iMessage.

My apologies for the unwarranted cynicism, I was not aware.

Re: Apple File System

#204

Post by brigade »

STRML wrote: post #113
MBCook wrote: post #102

Earlier quoted context omitted.

Is compression really that big a deal any more?

While they're still shipping machines with < 1TB SSDs (read: for a long time), yes - why not take the relatively free space and I/O savings?

On the other hand, people (sample size: my family and friends) tend to fill up their drives with already-compressed video and photos, which lz4 and similar cannot really compress further.

Re: Apple File System

#206

Post by nisa »

derefr wrote: post #126
skrause wrote: post #19

No checksumming?

Heck, if someone's going whole-hog on file integrity, I'd really like them to support the creation of files that are stored "expanded" by a fountain-code. Rather than having to RAID-mirror every block on my disk, I'd like to be able to pick just some files and say "please store those ones slightly more redundantly, such that they're protected from bit-level disk errors—they're important."

something like zfs copies=n? I used this on a drive with tons of bad sectors and it worked flawless - ZFS even spreads the writes throughout the disk. However AFAIK this is a property of using merkle hash trees (just add multiple leaves) and it's probably unlikely that Apple went this way.

Re: Apple File System

#207

Post by wcummings »

rleigh wrote: post #200

While I am happy that Apple have at last committed to replacing HFS+, I'm wondering why they didn't use ZFS rather than reinventing the wheel. It's not like it's a particularly easy wheel to reinvent either; the amount of effort which goes into a filesystem like ZFS is non-trivial. Why not build on top of that? I would have greatly appreciated being able to use ZFS with MacOS X, for datasets, snapshots, sending them…

How does AAPL feel about the CDDL?

Re: Apple File System

#208

Post by tptacek »

DannyBee wrote: post #50
cpr wrote: 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…

"FileVault: APFS volumes cannot currently be encrypted using FileVault. " This one is confusing, because this is a logical volume feature. Not sure how or why APFS would ever care that some layer above it is encrypting stuff.

What would be really neat is if this is because FileVault is going to be filesystem-level when they ship APFS.

It's wishful thinking, I know.

Re: Apple File System

#209

Post by feld »

MBCook wrote: post #102
jbergstroem wrote: post #30

No snapshotting yet, can't boot, no migration tools for existing setups (time machine, filevault, fusion). It'd be interesting to see whether their permission changes introduced in 10.11 will travel further down the fs. Also, I don't see any mention of compression like lz4. Lots of work until release in 2017!

Is compression really that big a deal any more?

Yes, it can make I/O faster

Re: Apple File System

#210

Post by watersb »

If you create a ZFS filesystem on a non-macOS, you have to be careful about Unicode mapping in order to use it safely on MacOS.

I have no idea if Unicode is an issue for Apple File System.

Emoji file names, you guys.

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