Report: ZFS is now ‘officially’ supported in Apple’s Mac OS X Leopard

“Back in May of this year it was rumoured that Apple’s File System Development Team had contacted Sun Microsystems to help in a translation of the Zettabyte File System to Mac OS X,” Alex Brooks reports for World of Apple.

“With the most recent Build of Mac OS X 10.5 Leopard, ZFS has appeared to have finally made an appearance, as per the rumours,” Brooks reports. “…Everything on ZFS is checksummed meaning zero data corruption.”

Overall ZFS offers the following key advantages:
• Pooled storage – No requirement for a volume manager when extra volumes added, the volume is simply added to a pool creating a vdev (virtual device), a collection of vdevs makes up a zpool, which in essence is the storage available to the file system.
• Snapshots – Read-only point in time of the file system
• Clones – write-able copy of a snapshot
• RAID-Z – Makes use of copy-on-write; rather than overwriting old data with new data, it writes new data to a new location and then overwrites the pointer to the old data
• Detects and then corrects data corruption
• Incredibly fast due to intelligent pre-fetching, and dynamic striping.

More in the full article, including a screenshot fo ZFS in Mac OS X 10.5 Leopard’s Disk Utility application here.

“A French user has discovered that ZFS is now ‘officially’ supported in Leopard [French], while testing the latest build of Apple’s upcoming operating system. Indeed it is now possible to create disk images or partitions formated in ZFS (screen capture included). However, it seems that it is not possible yet to install the OS on a ZFS partition,” OS News reports.

Sun Microsystems’ describes ZFS:
ZFS is a new kind of filesystem that provides simple administration, transactional semantics, end-to-end data integrity, and immense scalability. ZFS is not an incremental improvement to existing technology; it is a fundamentally new approach to data management. We’ve blown away 20 years of obsolete assumptions, eliminated complexity at the source, and created a storage system that’s actually a pleasure to use.

Much more information here.

Back in August, Ars Technica’s John Siracusa wrote, “For Mac geeks of a certain persuasion, the first mention of a soon-to-be-revealed feature of Leopard during the WWDC keynote set off a mental chain-reaction. That feature was Time Machine, and the name alone was enough to cause one particular phrase to hammer in the mind of many people, including me: ‘New file system in Leopard!’ …Maybe Apple is moving to ZFS in Leopard!”

MacDailyNews Take: If true, this is quite a big deal and qualifies as a major Leopard feature.

[Thanks to MacDailyNews Reader “LinuxGuy and Mac Prodigal Son” for the heads up.]

[UPDATE: December 17, 9:18am EST: Added World of Apple quotes and link.]

Related article:
Apple’s Mac OS X Leopard to feature new file system? – August 16, 2006


  1. Captain Obvious:

    I’ve done various kinds of backups for years, what sort can’t be done without ZFS? I’m just curious why people say Time Machine requires ZFS… couldn’t a simple Spotlight search for files modified since the last backup be done, then those files copied over to a Time Machine hierarchial folder structure?

  2. Don,

    The advantage of ZFS is exactly this: That it does not require copying the modified files in order to back them up. Once a file is modified the original version is merely marked as a “snapshot” of an older system state, with the advantage that the data being backed up does not need to be moved (copied) to another location. As a result, backing up under ZFS is a tremendously fast process.

  3. Time Machine can be done without ZFS or any new file system. This support in Leopard indicates Apple may be looking toward the future (perhaps the next major release after Leopard), when all new Macs will move to a new more modern file system. At that point, users of existing Macs can continue with HFS+ with some new features unsupported, or do a backup and reformat for ZFS.

    Interesting news… I’m getting psyched for Leopard.

  4. One feature of ZFS that will be welcomed is pooled storage!

    Think beer. Instead of putzing around with cans or bottles of beer, having a keg on ice is so much better. And cheaper, I might add.

    Pooled storage obviates the need for volume formatting, partitioning and the creation of sectors. The system sees all physical drive space as one massive storage pool and actually writes to discs using exactly the space it needs to store your files. No more wasted sectors when writing small files to them.

    Say goodbye to FSCK too.

    I hope this is true.

  5. I just read the wiki on ZFS, and am officially more confused than ever about how it works – except that it stores data more efficiently and has no device manager. I had been wondering since the last keynote how Time Machine was ever going to be practical with the storage limitations of most users.

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