updated 10:10 pm EDT, Tue June 12, 2012
Removal may force university IT, researchers to find new solutions
OS X Mountain Lion was officially unveiled on Monday, and is shipping in July -- but conspicuously absent from the list of features is Apple's ad-hoc supercomputer tool Xgrid. Apple's Xgrid provided network administrators a means of constructing a Beowulf cluster, allowing them to use computer idle-time to drive calculations that can be divided into smaller operations. Xgrid client has been installed in all computers running OS X 10.4 or greater by default, so installation and configuration of a massively parallel grid was completed with little time or money outlay. The job controller is included in Mac OS X Server up to OS X Lion and as a free download.
Architecture of a Xgrid-enabled supercomputer is fairly simple: a client computer submits a job to the controller, the controller receives the job from the client, the controller breaks up the job into manageable segments and distributes them to the distributed computers -- the agents. The agents perform the calculations, and send the data back to the controller. One task per CPU per computer can be submitted, so an eight-core Mac Pro can receive and process eight jobs simultaneously. Jobs are performed as CPU and system resources allow -- if a job has been submitted to an agent, and a local user starts using the agent again, then the job is either slowed or suspended as to not interfere with the user's task. When the job is completed, the controller reports back to the client with the results.
At the end of development, popular video application VisualHub integrated Xgrid technology into its codebase to speed time-consuming video transcoding, generally to the H.264 codec for the then-new Apple TV and iPod Video and touch. The 3D modeling application Blender was able to use an Xgrid cluster to direct a network of Macintoshes as a rendering farm.
The most famous Xgrid setup was at Stanford University, in the Molecular and Cellular Physiology department performing calculations for pharmacology research. Following an influx of users, the team generated 400-600GHz of processing power in September 2006.
The absence of Xgrid capability in Mountain Lion won't affect most users, but educational institutions lacking the budget for a dedicated supercomputing grid will find future efforts hampered, or face declining processing power as users upgrade to Mountain Lion. Supercomputers like the Mac Pro-based Big Mac and previous G5-oriented System X cluster at Virginia Tech didn't consistently use OS X through their entire lifetimes, much less Xgrid, so either wouldn't have been affected by Apple's removal even in its heyday.
Apple hasn't made any official announcement about the future of Xgrid. The technology has languished for the last few years. With the absence of Xgrid as a feature in OS X Mountain Lion server, and no sign of it in the Developer's Preview of the client, signs are pointing to a departure of the eight-year-old base technology, once a selling point of the operating system.