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. 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.

  2. ZFS is kinda fresh and not yet completelly ready system.


    ZFS is currently not available as a root filesystem since there is no ZFS boot support. The ZFS Boot project is currently working on adding root filesystem support.[6]
    ZFS lacks transparent encryption, a la NTFS, although there is an OpenSolaris project underway.[7]
    ZFS doesn’t support per-user or per-group quotas. Instead, it is possible to create user-owned filesystems, each with its own size limit. The low overhead of ZFS filesystems makes this practical even with many users.
    RAID-Z doesn’t support capacity expansion. It is possible to expand the array by iteratively swapping each drive in the array with a bigger drive and waiting for ZFS to heal itself – however this method is prohibitively expensive.

  3. “That makes Microsoft scrapping WinFS in Vista even more pathetic and humiliating if true.”

    Yes Apple is showing much greater engineering prowess than Microsoft by taking a public domain file system and incorporating it.

    NTFS already includes many of the key features of ZFS. This is more Apple playing catch up rather then making a huge forward leap.

  4. I can see the Vista marketing/FUD machine getting ready:
    — Don’t use Macs – they cause massive global warming!
    <quote>Thus, fully populating a [ZFS] 128-bit storage pool would, literally, require more energy than boiling the oceans. —Jeff Borwick, Leader of FZS Desing Project & CTO of Storage Technologies at Sun Microsystems</quote>

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