Apple kicks ZFS in the butt

Apple promised ZFS on Snow Leopard - and didn't deliver. A Mac's data integrity is now no better than Windows. And that's not good enough.
Written by Robin Harris, Contributor

It's official: ZFS - a kick-butt file system - is nowhere to be seen in the latest release of Mac OS X, Snow Leopard. Even though it appeared in 10.5 Server, and was expected to become the default file system at some point, Apple has abandoned the Sun-developed ZFS, the first 21st century file system.

A bummer for anyone who stores data on their computer.

Why should I care? Apple is hoping you don't - and they're probably right. None of the mainstream press have mentioned dropped feature, even though it is right up there with parallel processing support as a winner for users.

ZFS combines a file system and a volume manager, along with some cool architectural features, to create an easily managed and highly reliable file system. Advanced features that just work.

Some cool features.

  • Manage storage, not disks. You can put all your disks in a pool and specify the redundancy level. ZFS takes care of the rest.
  • No more silent data corruption.Wonky things can happen to your data to and from a disk. ZFS checksums every file before it is written and stores the checksum on the parent. When the file is read, the checksum tells the filesystem if that is the block it wrote.
  • Easy snapshots. Ever wish you could roll back to a known good state? Snapshots make that easy and ZFS makes snapshots easy.
  • High performance software RAID built-in. Worried about protecting your data. ZFS provides strong RAID capabilities without adding hardware.
  • Transparent compression on the fly. Save capacity by compressing old and/or large files automagically.

What happened? 2 years ago it looked like ZFS was locked in to Snow Leopard. The Apple team was working with the Sun ZFS team. It was enabled as a read-only file system on 10.5 server. Apple even freakin' announced ZFS on Snow Leopard. The advantages - to storage geeks - were obvious.

Plus the opportunity to put daylight between OS X and Windows 7. Microsoft's ambitions for something called WinFS crashed to earth 3 years ago (see Bring me the head of WinFS.

But Apple started walking back ZFS about 9 months ago. Newer builds of Snow Leopard had less and less ZFS content until today's official release - which has none.

Maybe some insight will emerge from secretive Apple, but don't count on it. Removing ZFS from the server edition, where it makes even more obvious sense, suggests it is gone for good.

What did it in? Maybe it was a schedule problem - file systems require a lot of testing - and rewriting all the other bits took precedence. NIH - Not Invented Here - syndrome is another possibility. Or perhaps the uncertainty of Sun's future led Apple to pull back.

Or maybe they just decided customers wouldn't know enough to care, so why bother? Whatever the reason it is a major step backwards for the PC industry.

The Storage Bits take File systems are essential but unsexy plumbing. Whether it's a missing or corrupted file or a system slowing to a crawl because the directory is bloated, there is no error message that says "Your FS is screwed up."

And as noted in How Microsoft puts your data at risk - which indicted Apple's HFS+ as well -

. . . more than half of all data loss is caused by system and hardware problems. A high quality file system that took better care of our data could eliminate many of those failures.

The industry knows how to fix the problems. The question is when. With a resurgent Mac pushing ZFS maybe Redmond will see the light sooner, rather than later, and dramatically increase the reliability of all our systems.

With Apple's retreat from ZFS everyone who uses a personal computer is the loser. Maybe the Microsoft team working to improve NTFS will now take the lead in file system quality and feature.

Comments welcome, of course. Update: I got some more theories over the weekend on why the ZFS deal fell through. Check them out on StorageMojo. The short answer: licensing; GPL vs CDDL. End update.

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