Some Mac users are demanding that Apple add modern file system support in the next major version of OS X. An online petition has been started to let Apple know that its aging HFS+ file system just won't cut it any more, and the company should include ZFS in OS X 10.9, expected later this year.
HFS+ is the current file system used by OS X (and iOS). It was originally developed as HFS, or "Hierarchical File System," for the original Mac OS in the early '80s. A team at Apple, led by engineer Don Brady, adapted HFS for 32-bit systems in the mid-1990s. Brady later adapted HFS+ to work with the UNIX environment that OS X was built on, and over time he and other Apple engineers added additional features, including the extensible metadata used by Mac OS X's Spotlight search, live partition resizing used for Boot Camp, and the Adaptive Hot File Clustering used to reduce seek times for oft-used system files.
Despite all the features Apple has managed to tack on to HFS+, though, its design certainly isn't modern. "The initial HFS+ was primarily about addressing the block count problem," Brady told Ars in 2011. "Since we believed it was only a stop-gap solution, we just went from 16 to 32 bits. Had we known that it would still be in use 15 years later with multi-terabyte drives, we probably would have done more design changes!"
ZFS, on the other hand, was designed from the ground up to address the ever-increasing needs for large amounts of storage, as well as the need to protect data as it is written to and read from disk. As a 128-bit native file system, ZFS can address up to a theoretical 256 quadrillion zettabytes. One zettabyte alone is equivalent to over a billion terabytes; 256 quadrillion billion terabytes is more storage space than could practically be used on Earth. It also includes several features designed to ensure the integrity of data on the disk, including checksumming every block of data so the system knows if a block goes "bad" and RAID-like features that allow disks to "heal" themselves if data corruption is detected.
Apple actually flirted with ZFS early on in its development. Brady was involved in a "skunkworks" project to port ZFS to OS X that started in 2005. Some of the code shipped in Leopard (10.5) and was expected to be a major feature of Snow Leopard (10.6). But due to licensing issues with Sun (and perhaps other reasons), Apple dropped all support for ZFS in Snow Leopard and cancelled the open source project that had served as official support for ZFS on OS X. (That project was forked and still exists as MacZFS.)
Brady later left Apple and started his own company to build a commercial version of ZFS for OS X. He got as far as releasing a command line "community" version called ZEVO before his company was acquired by enterprise software maker GreenBytes in June 2012. GreenBytes still offers the free community version of ZEVO while Brady continues to work on a GUI version that can integrate with OS X (though restrictions like sandboxing have proven difficult to work around).
Still, some users want official support for ZFS "or its equivalent" from Apple, and they want it soon. Mac user Thomas Monte started an online petition practically demanding that Apple add modern filesystem support to OS X 10.9.
(The petition also asks Apple to update the ancient OpenGL support in OS X, which still lags Windows significantly, from version 3.2 to the latest 4.3. Previous sources have indicated that improved OpenGL support is indeed coming.)
Unfortunately, the demand for ZFS support may fall on deaf ears. Aside from the fact that Apple hasn't shown any indication that it will support anything other than HFS+ for the time being, OS X 10.9 is already showing signs that it is being widely tested internally at Apple. It is also likely to get its first public showing in the next several weeks, and if Apple keeps to its projected one-year development cycle, it could be released this summer.
Still, it's been 30 years since Apple originally developed the basis for the file system currently used in OS X. Whether Apple adopts ZFS, Oracle's BtrFS, or is secretly rolling its own modern file system, OS X is long overdue for something new.
reader comments
172