FAQ: Is ZFS Apple's secret weapon?

Computerworld - Apple Inc. collects secrets like a pack rat collects shiny things. It's part of the company's culture. So when someone breaks the code of silence, it sets virtual seismographic needles scratching. That happened this week, when Sun Microsystems Inc.'s CEO Jonathan Schwartz said Apple's upcoming Mac OS X 10.5 Leopard, would rely on a file system that engineers at his company have spent years creating: ZFS.

ZFS? As in Zurich Financial Services? Or Zeppelin Flight School?

Just what is ZFS, and why did it send Mac enthusiasts spinning? Read on. ...

What does ZFS stand for? At one time, it was an acronym for Zettabyte File System, but Sun now prefers that the name stand on its own. "Zetta," by the way, is one of the standard SI prefixes -- as are the much more familiar "kilo," "mega" and "giga" -- and represents 1021, or 100,000,000,000,000,000,000. According to Sun, "The largest SI prefix we liked was 'zetta.'" Sun was obviously seeking to evoke a really big number to remind everyone of the file system's data (and number of files) capacity. Sort of like Super Size Me -- the movie -- but bigger. Way bigger.

Got it. Now what is it? ZFS is a 128-bit file system that Sun announced in 2004 but didn't integrate with its Solaris operating system until 2006. Among ZFS's selling points is huge capacity, storage pooling, fast data snapshots and copy-on-write. As a 128-bit file system, it can store 18 billion billion times more data than current 64-bit systems, such as NTFS, which is Microsoft Corp.'s file system for Windows. According to calculations on Wikipedia, it would take about 9,000 years to max out ZFS's file limit if 1,000 files were created every second. Pooling eliminates partitions, and much of the hassle with storage, such as figuring which "volume" to stick files on, or how to manage a new external drive.

"You don't have to worry about the details of what's going on with your disks, your storage or your file systems," Jeff Bonwick, chief architect of ZFS, said when Sun rolled out the file system in 2004. "You add disks to your storage pool, file systems consume space automatically as they need it, and administrators don't have to get involved." And copy-on-write, which copies modified data to a new block rather than overwriting existing data, is pertinent here because it's one of the most-common methods used to take quick "snapshots" of a disk (or in the case of ZFS, the storage pool) as point-in-time backups.

OK. So why am I hearing about ZFS now? Blame Schwartz, who at one point during a new product introduction on Wednesday spilled what sounded like a secret. "This week, you'll see that Apple is announcing at their Worldwide Developers Conference that ZFS has become the file system in Mac OS X," he said. Most alert listeners keyed on the word "the," and heard it as in "the default" or "the only." Swap out the Mac's 22-year-old Hierarchical File System? Between now and October? Wow. The supposition seemed confirmed when a second exec, Marc Hamilton, Sun's director of technology for global education and research, wrote on his blog that "Jonathan noted that Apple will announce this week that the ZFS file system from OpenSolaris will become Apple's new default file system [emphasis mine]."