CPU scavenging
CPU-scavenging or cycle-scavenging systems use machines purchased for other purposes to run batch jobs at night, weekends, and other idle times.
Cycle-scavenging systems typically gain and lose machines at unpredictable times as interactive users start or stop using their machines, new machines are purchased, machines are removed from the network, or break down. Cycle-scavengers move jobs from machine to machine as necessary to allow the smooth running of the job and the network being scavenged.
Cycle-scavenging systems are also referred to as computational grids or shared computing grids.
Projects
The best-known cycle scavenging computation is SETI@home, currently the largest computation on the planet. SETI@home was using more than 3 million computers to achieve 23.37 sustained teraflops (979 lifetime teraflops) as of September 2001 [1].
As of May 2005, Folding@home had achieved peaks of 186 teraflops on over 160,000 machines.
Another well-known project is distributed.net, which was started in 1997 and has run a number of successful projects in its history.
The NASA Advanced Supercomputing facility (NAS) has run genetic algorithms using the Condor cycle scavenger running on about 350 Sun and SGI workstations.
United Devices operates the United Devices Cancer Research Project based on its Grid MP product, which cycle scavenges on volunteer PCs connected to the Internet. As of June 2005, the Grid MP ran on about 3,100,000 machines [2].
Parabon Computation provides services similar to United Devices, but claims that it is safer to the machines from which the cycles are scavenged as Parabon's client software operates within a Java sandbox.
See also the List of distributed computing projects for other public projects.