Mac OS X 10.2.2 Gains Journaling

The new feature in the server version of Apple's OS will speed recovery from crashes, the Mac maker said.

Apple Computer Inc. turned a new page for Mac OS X on Monday when it took the wraps off a new journaling feature for the Unix-based operating system.

Apple delivered the journaling technology alongside the server configuration of Mac OS X 10.2.2; both client and server versions of Version 10.2.2 are available now for download.

eWEEK last month reported that Cupertino, Calif.-based Apple was readying the journaling feature, code-named Elvis. Sources said that the project was spearheaded by Dominic Giampaolo, who joined Apple in March as a file system engineer after creating the journaling BFS for Be Inc.s OS.

According to Apple officials, the new journaling technology extends the Mac OS HFS+ file system, is fully compatible with HFS+ and can be applied to current Mac OS volumes without reformatting. Users of Mac OS X Server can activate journaling by clicking on a "Make journaled" button within the Disk Utility application, the officials said. They can also access it via the command line or remotely via a Secure Shell (SSH) connection.

The journaling scheme automatically logs file system transactions to guarantee file system consistency in the event of a crash. Journaled systems can retrieve lost data by consulting the "journal" log, restoring the system to its previous state instead of having to go through the lengthy process of rebuilding it via Unixs file system consistency check (a BSD command that works with HFS file systems) or similar disk-check utilities.

A number of Unix systems (including some Linux distributions) and the current version of NTFS, the file system within Windows 2000 and XP, include journaling capabilities.

"Because journaling does not safeguard the actual contents of files or prevent data loss resulting from a hardware failure, it should be used in conjunction with protected RAID storage and an appropriate backup strategy," Apple wrote in its technical documents. Apple has announced plans to release RAID hardware for its rack-mounted Xserve server, although the company has not yet specified pricing or a ship date.

Sources told eWEEK that the journaling option reduces system performance by 10 percent to 15 percent; Apple representatives were not immediately available to comment on the performance issue.

According to Apples documentation, Mac OS 10.2.2 offers a variety of performance tweaks and compatibility fixes for peripheral devices, networking and the OS address book and mail utilities. Apple also offers a full account of the latest enhancements to the server package.

Mac OS X 10.2.2 is the second interim upgrade to Apples Unix-based OS since Jaguar shipped for $129 on Aug. 24. Sources predicted a 10.2.3 update will ship in time for Januarys Macworld Expo/San Francisco, the date when Apple CEO Steve Jobs has announced new Mac models will no longer boot into Mac OS 9. The next major upgrade, code-named Panther, is slated to ship in 2003.