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ZFS for Mac OS X Breaths New Life

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Re: ZFS for Mac OS X Breaths New Life

#31

Post by ciupicri »

newman314 wrote: post #28
johnthedebs wrote: post #24

Earlier quoted context omitted.

Without encryption, compression, or deduplication on I don't think there would be very much overheard - more than traditional file systems, definitely, but still relatively very little. Encryption would require significantly more CPU ( http://forums.freebsd.org/showthread.php?t=9886 ) Compression would require moderately more CPU (depends heavily on the compression algorithm) though you can actually speed up disk acc…

With new Core iX processers now being able to do AES in hardware, I wonder if the CPU requirement for encryption will go down significantly once/if support is enabled.

Not all Core iX processors have support for the new AES instructions.

Re: ZFS for Mac OS X Breaths New Life

#32

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Re: ZFS for Mac OS X Breaths New Life

#33

Post by petsos »

Someone wrote: post #23
ComputerGuru wrote: post #12

What I'm actually more interested in is what Apple is intending on using instead of ZFS. All indications are that ZFS will not be the next filesystem for OS X, yet they'll need to replace HFS soon seeing as it's the worst-performing and fewest-featured filesystem in use with this generation of operating systems. HFS+ is showing its age in multiple places, and Apple could really take advantage of some of the newer fea…

AFAIk the main argument against use of ZFS is that it would be relatively resource hungry, making it a bad candidate for use in e.g. A MacBook Air. I have Googled, but couldn't find recent data about this. Does anybody know about any? If performance isn't good enough on some target hardware, could one do better, or would it require dropping features? Which ones?

I don't know how resource hungry ZFS is, but the problem would be with the iOS devices, not MacBook Air.

Re: ZFS for Mac OS X Breaths New Life

#34

Post by joubert »

ZFS is fantastic; it was my file system when I ran Solarid on my Sun workstation (until I replaced it with Ubuntu).

I did get bitten once, wiping out a whole bunch of data very unexpectedly, which I thought was a great ZFS weakness - http://www.mail-archive.com/zfs-discuss@opensolaris.org/msg0...

Re: ZFS for Mac OS X Breaths New Life

#36

Post by zdw »

wtallis wrote: post #16
ComputerGuru wrote: post #12

What I'm actually more interested in is what Apple is intending on using instead of ZFS. All indications are that ZFS will not be the next filesystem for OS X, yet they'll need to replace HFS soon seeing as it's the worst-performing and fewest-featured filesystem in use with this generation of operating systems. HFS+ is showing its age in multiple places, and Apple could really take advantage of some of the newer fea…

Don't forget about the block-level deduplication and copy-on-write which would make Time Machine use much less space.

Time Machine uses hard links within it's directory structure, so dedupe or CoW wouldn't be much help unless it was redesigned using ZFS specific features (ie, instead of rebuilding an entire hard link structure as TM does, you'd clone the TM filesystem, then apply the source changes).

Re: ZFS for Mac OS X Breaths New Life

#37

Post by zdw »

johnthedebs wrote: post #21
BonoboBoner wrote: post #20

What I am interested in is, are there any ZFS patents that Oracle could use to sue Apple once they eventually broadly ship ZFS?

Apple won't be broadly shipping ZFS, which they made pretty clear when they pulled it from Snow Leopard. They haven't made an official statement, but the general consensus is that they couldn't agree on licensing terms with Sun (ZFS is licensed under the CDDL) and so they bailed on it. Oh how I wish they had worked things out. That said, Oracle is also unlikely to do them any favors.

It's not CDDL - Apple has shipped dtrace for years now which is CDDL code.

Most likely, ZFS was written off for various technical reasons (large RAM requirements to run well, not optimized for portable hardware, etc.) and if there was a legal issue it was probably the NetApp lawsuit against Sun regarding ZFS.

Re: ZFS for Mac OS X Breaths New Life

#38

Post by zdw »

johnthedebs wrote: post #24
Someone wrote: post #23

Earlier quoted context omitted.

AFAIk the main argument against use of ZFS is that it would be relatively resource hungry, making it a bad candidate for use in e.g. A MacBook Air. I have Googled, but couldn't find recent data about this. Does anybody know about any? If performance isn't good enough on some target hardware, could one do better, or would it require dropping features? Which ones?

Without encryption, compression, or deduplication on I don't think there would be very much overheard - more than traditional file systems, definitely, but still relatively very little. Encryption would require significantly more CPU ( http://forums.freebsd.org/showthread.php?t=9886 ) Compression would require moderately more CPU (depends heavily on the compression algorithm) though you can actually speed up disk acc…

ZFS lets you put encryption/compression/dedupe on a per filesystem basis, and filesystems are extremely light and easy to create in ZFS (one/multiple per home directory or installed app is normal) so it's easy enough to only apply those features where they're needed.

As ZFS checksums every block in the CPU anyway, doing an additional crypto step isn't all that bad, especially in a server environment where there cores are plentiful.

Re: ZFS for Mac OS X Breaths New Life

#39

Post by ComputerGuru »

johnthedebs wrote: post #30
ComputerGuru wrote: post #25

Earlier quoted context omitted.

Really the biggest culprit is Mail.app - so this would depend on how big your Mail archive is.

The reason deduplication won't help much with large mail archives is that it operates at the block level. In order to be effective, you need to have two copies of the same data that are also divided along the same block boundaries (the second part is arguably the bigger problem). Also, many applications will already try avoiding duplicate data to varying degrees which makes dedup even less beneficial (backup utilitie…

You're missing my point: it's not duplicate blocks in a single mail archive that I'm concerned about, it's duplicate blocks across multiple versions of the same mail archive.

New mails are typically appended to the end of the archive, but the rest of it remains more or less the same across versions.

Also, a well-written block-level deduplication algorithm will work regardless of boundary shifts. I designed and wrote the proprietary blocklevel algorithm used in Genie Timeline, and can tell you that it saves terabytes of data in corporations for just PSTs alone. And it doesn't rely on block boundaries, capable of detecting slided or shifted data.

Re: ZFS for Mac OS X Breaths New Life

#40

Post by nilio »

BonoboBoner wrote: post #20

What I am interested in is, are there any ZFS patents that Oracle could use to sue Apple once they eventually broadly ship ZFS?

I think a side community project is perfect given this potential concern (even though likelihood is unlikely). Oracle's not going to sue Apple for something like this.
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