Getting Started with Condor
Another way to link distributed Condor pools together is by using Condor's grid computing features, which utilize the Globus Toolkit (www.globus.org). The Globus Toolkit is an open-source software toolkit used for building Grid systems and applications. It provides an infrastructure for authentication, authorization and remote job submission (including data transfer) on Grid resources. Condor-G, an extension of Condor, provides all of Condor's job submission features, but for far-removed resources on the Grid.
Condor-G is sort of a gateway to the Grid for Condor pools. Condor-G is a program that manages both a queue of jobs and the resources from one or more sites where those jobs can execute. It communicates with these resources and transfers files to and from these resources using the Globus mechanisms. For more detail on setting up Condor-G, consult the Condor Manual mentioned previously.
A sample submit file for a job to be executed over Globus looks like this:
executable = mygridjob globusscheduler = grid.sample.net/jobmanager input=mygridi.txt universe = globus output = mygridjob.out log = mygridjob.log queue
As you can see, there are only two differences with Grid jobs and normal local pool jobs. The Universe is Globus, which tells Condor that this job will be scheduled to the Grid. And, we specify the globusscheduler, which points to the Globus Job manager at the remote site. The jobmanager is the Globus service that is spawned at the remote site to submit, keep track of and manage Grid I/O for jobs running on the local system there. Grid jobs can be monitored the same way as ordinary Condor jobs with condor_q.
Condor provides the unique possibility of using our current computing infrastructure and investments to target processing of jobs that are simply beyond the capabilities of our most powerful systems. Condor is easy-to-install and easy-to-use software for setting up clusters. Condor is scalable. It provides options to extend its reach from a single cluster to interconnecting clusters that can be located anywhere in the world. Condor has been fundamental software for many grid computing projects. Various success stories with Condor have been reported in the press. One of the recent ones is of Micron Technologies. Micron is one of the world's leading providers of advanced semiconductor solutions. In an interview with GridToday in April 2006, a senior fellow at Micron said that they had deployed 11 Condor pools consisting of 11,000 processors, located in four countries in seven different sites. Why Condor? Because it supported all the platforms Micron was interested in, and it was already widely used, well supported, and of course, it was open source. These pools have become a vital asset for Micron. They are used for everything from manufacturing, engineering, reporting and software development to security. Condor is not only a research toy, but also a piece of robust open-source software that solves real-world problems.
Irfan Habib is an undergraduate student in software engineering at the National University of Sciences Technology Pakistan. He has been deeply interested in free and open-source software for years, and he does research in Distributed and Grid Computing. Condor combines both of his interests. He can be reached at firstname.lastname@example.org.