I mentioned over a year ago that Apple was porting Sun’s ZFS file system to Mac OS X. While it was available as read-only on Leopard it seems to have been completely pulled from Snow Leopard. For something that was suspected to be the future of disk storage for Mac OS X, that seemed odd. Now Apple has officially discontinued the project.
I had heard about the ongoing NetApp vs. Sun patent war where NetApp feels that ZFS is too close to WAFL. It seems likely that Apple doesn’t want to get involved in that. Apple even has a fear of that potential with OGG Theora. Once the transition was made to ZFS it would be a costly and time-consuming effort to swap with something else since Mac OS has never been very file system neutral.
A new theory is that the Oracle/Sun deal leaves the company developing two filesystems: ZFS and Btfs. It sounds like Oracle’s Btfs is the more likely future. If Apple switched to ZFS they would have been left as the only platform using it. Linux can’t fully switch since the CDDL license isn’t fully compatible with GPL meaning it would need to be implemented through FUSE. Btfs is coming along for Linux.
Reading through Btfs, it seems like a lot of the big advantages of ZFS are already in Btfs though it lacks full disk encryption. It does however add online resizing. It’s also GPL and has support from RedHat, Novell, IBM and was accepted into the Linux mainline kernel as of 2.6.29rc1. That means it already has a much more robust community and seems likely to be widely accepted in UNIX land.
So will Apple switch to Btfs for Mac OS X 10.7 or 10.8? I think the two possibilities are that it will either build something in-house, or switch to Btfs. I think Btfs offers a compelling set of features and would allow Apple to brag about more compatibility with other OS’s and potentially adopt features as the file system matures at a low-cost. It’s possible we’ll hear something as soon as WWDC 2010.