Update: In the comments Mark claims that the ZFS reference in Apple’s Leopard, the next version of Mac OS X, proves that Apple is, in fact, working on porting ZFS:

All filesystems on MacOS X are implemented using what’s called VFS plugins, these interact with the kernel. The vnode is the focus of all file activity, that list tells me that the vnode is now ZFS aware which means there is or was a corresponding VFS plugin in a lab somewhere.

Look at the file list, those are all the VFS types the MacOS X XNU kernel supports…+1. If they’ve added ZFS to the vnode.h list it means it was or has been in development. If it was in development it’ll vanish from that list when the next build is released, if it still is in development it’ll stay.

I haven’t seen this interpretation anywhere else, so I’m off searching for independent confirmation, as I don’t have the Unix chops to make heads or tails of it. Yet for those of us who want to see computing’s state of the art advance this is a heartening thought.

Thank You, John Siracusa
Ars Technica’s John Siracusa went out of his way to make me [where “me” = the class of folks who thought Apple’s new Time Machine meant ZFS on Leopard] feel better in his recent post Time Machine and the future of the file system when he said

. . . it’s seemed like accepted wisdom among the denizens of Mac web forums and blogs that Apple was moving to ZFS. Time Machine seemed like an official confirmation of what everyone expected. Just google for “zfs leopard snapshots” to see how many people came to the same conclusion when Time Machine was announced. All the pieces fit. Too bad it’s not true.

The snapshot/ZFS revelation was debunked nearly as quickly as it sprang up. Although all of WWDC except for the keynote is covered by an non-disclosure agreement, the particulars of Time Machine’s implementation were some of the very first technical details to leak.

Leak Here First!
And some of that leaking first occurred here on StorageMojo.com, I’m pleased to say. See the comments to the post Is Apple’s Time Machine Built On Sun’s ZFS?. If you are wondering why ZFS is cool, see ZFS: Threat or Menace? Pt. I.

But Wait! There’s More!
Over at this Apple Insider thread someone had the bright idea to ask a Leopard beta user to search for references to ZFS. And guess what? He found one:

Originally Posted by shadow
Someone who has Leopard: go to Spotlight and search for ZFS. Got something?

Yes. There is no file system bundle for it, nor is there a mount utility or any other one (no fsck, now newfs, etc.). There is, however, a changed vnode.h:
enum vtagtype {

I Have No Idea
What including ZFS in an incomprehensible list means, if anything. I don’t feel too bad, because none of the smart folks on that forum seemed to know either.

So, John, Why Do You Say That?
While not holding out any hope of ZFS on Leopard, John did allow as how

. . . what I did expect was a new file system from Apple. Not a port or a fork of an open source file system, but a brand-new, home-grown, kick-ass file system created by Apple’s own team of engineers.

John, why fan the flames of Apple’s NIH syndrome? With some exceptions, Apple is not a plumbing company, and file systems are plumbing. Sun supported the ZFS team for six years while they built ZFS. What is the chance of Apple mounting a similar effort? Somewhere between zip and near-zip IMHO.

The Takeaway
StorageMojo.com has devoted time to this issue because today’s computer business is largely driven by consumer computing, not enterprise computing. Putting a really modern integrated file and storage management system on a consumer OS would raise the bar for everyone else. Until something better happens along, ZFS appears to be the best option. Here’s hoping the Apple engineering gnomes are beavering away to port ZFS to an Apple OS near us. Soon.