Proof that OS X Leopard will use ZFS? - Time Machine Revealed?

by Sam Griffith

Over on SUN's ZFS web site, you'll find an interesting little article about ZFS snapshots.... (notice the screenshots) ;-)

I think you'll find it similiar enough to confirm that OS X Leopard will have ZFS as it's main file system. All I can say is "Awesome" Read more about ZFS to see why I'm so excited about OS X having the most advanced file system ever.

Since I took so long to write this several people beat me to the punch on posting. (I started it on 8-8-2006 and got sidetracked with some work things and didn't post it) The following is my favorite although I don't agree with the consclusions he comes too.:

And here are some more...
More about ZFS available at these links:

Screencasts of ZFS in action available from this page:


Andy Markham
2006-08-20 23:35:00
Your favorite article (the FatBits one) starts out by touting that ZFS must be in Leopard, but then later states that idea has been shot down since Time Machine details were some of the first leaked following WWDC. Am I missing something?
Dick Davies
2006-08-20 23:41:23
Yes, it sounds similar to ZFS snapshots, and I know apple are currently porting it.
But TimeMachine isn't ZFS based - it isn't even snapshot based.

Instead it uses a lot of hardlinking behind the scenes to mock up snapshots
on top of HFS+ (wasting a lot of diskage in the process):

If I had to guess, I'd say the backend might be reimplemented in a later release.

Sam Griffith Jr.
2006-08-20 23:48:39
Andy your not missing something. I forgot to mention that I didn't agree with his conclusions. I've updated the entry to say that. Thanks!
Sam Griffith Jr.
2006-08-20 23:50:43

Can I ask how you came by that information? To me those screenshots from the SUN site are too much of a clue.... plus, knowing that Apple had been interested in porting ZFS late last year/early this year, it would make sense that they'd have it running now and that by the time Leopard ships it would be completely done.

Sören Nils Kuklau
2006-08-20 23:55:45
I think you'll find it similiar enough to confirm that OS X Leopard will have ZFS as it's main file system.

Time Machine doesn't use snapshots or any kind of file system-level versioning. It relies, instead on hardlinks.

Sam Griffith Jr.
2006-08-21 00:03:19
I see that several people agree with the 'fatbits' article on the use of hardlinks. I'm not convinced right at the moment. Granted, if you are someone who went to WWDC and that's what your were told, then please go ahead and say that in your comment, so the rest of us know. But right now, I am still of the opinion that ZFS is being ported to Leopard, and will be done by the time it ships. (The Time Machine demo may have used some other means to do it's work) I think the screenshots on sun blog page (first link), the fact that Apple had been interested in porting ZFS, and the fact that they did port 'dtrace' all speak to Leopard having ZFS by next spring.
Dick Davies
2006-08-21 01:45:47
"Can I ask how you came by that information?"

Sure - on the zfs mailing list (the opensolaris guys have been in contact with apple):우

Dick Davies
2006-08-21 01:48:22

bleh. URL was mangled. Go to the zfs-discuss mailing list archive at:

and search for the thread called 'apple time machine'.

Sam Griffith Jr.
2006-08-21 06:39:02

Thanks for the link.... That's very interesting... It is sure wild considering the GUI ideas being very similiar, etc. I'm still hoping that they are porting ZFS even if Time Machine isn't using it right now... Thanks for the great info...

Sam Griffith Jr.
2006-08-21 06:52:42
This set of messages from April still makes me wonder though...螤

2006-08-21 07:17:23
Which part of the FatBits post at Ars Technica do you disagree with?
2006-08-21 07:53:32
Sorry, I didn't see the earlier comments when I posted mine above. Anyway, back on topic...

right now, I am still of the opinion that ZFS is being ported to Leopard...

It (almost certainly) is.

...and will be done by the time it ships.

It may be. But all of this is separate from the question of whether or not Time Machine uses ZFS snapshots. It does not. I wasn't at WWDC, but I assure you, you can take this information to the bank :)

Roger Weeks
2006-08-21 10:02:06
These screenshots are interesting, but they're certainly not from an Apple OS, if that's what you're intimating.

I can't remember the name of the Java-based GUI that you're looking at in the first screenshot on the web page, but it's a Sun-developed GUI. Those transparent angled windows are a dead giveway. I saw Sun demo'ing this at OSCON 2005 and LinuxWorld 2005 that year.

Dick Davies
2006-08-21 11:51:09
Hi Sam -

I'm sure ZFS will be in a future release. It has one or two rough edges (NFS performance under extreme load and fine grained quota support spring to mind), but nothing that would bother desktop users much.

But I suspect HFS' quirks (case insenstivity/sensitivity, resource forks etc) stop ZFS being easy drop-in replacement (even with Suns help, porting ZFS is a lot of work - have a google for 'ZFS fuse' to see what I mean).

Roger: it's "project looking glass".

Matej Cepl
2006-08-23 07:44:13
Sweet idea, except that this has been already refuted --



Sam Griffith Jr.
2006-08-23 19:11:21
I am not so sure... The demo might use HFS+ and hardlinks, but read this from today...

2006-09-24 01:42:59
Sam, it is GNOME desktop on all screenshots and not OS X.
Sam Griffith
2006-09-24 11:23:40
Dim - your right. That's why in the next paragraph I said, "I think you'll find it similiar enough...". Meaning that the Apple guys had probably seen something like this when they first talked to the SUN guys about wanting to port ZFS to OS X. Inspiring them in a way.
2006-12-21 05:06:04
If you actually read Sun's documentation, you'd know that they do NOT support ZFS as a root filesystem at this time. Unless Apple's finished the development on someone else's product for them, I doubt Time Machine will use zfs.
Sam Griffith
2006-12-21 06:08:17
Actually there are alpha versions of ZFS that boot (since August of last year - first link below). Read about it at these two links...

While this does not confirm 100% that Apple has ZFS boot-able for OS X Leopard on PPC and Intel, it is one more pointer to make the circumstantial evidence add up. Still not confirming it 100%, but looking more realistic every day!

Sam Griffith
2006-12-21 06:13:40
And GrumpyBob, I did read the ZFS docs and have followed it for months! If you try a Google search on "ZFS boot" you'll find more info...