====== Condor: Batch/Grid Computing ======
Batch-style processing is available on select nodes of the Unix cluster via Condor.

Condor is a software framework for distributed parallel computation. At Minnesota, we use it both to manage workload on dedicated server clusters, and (in some cases) to farm out work to idle desktop computers

Each Physics linux system is tagged with a "CondorGroup" name corresponding to the research group or entity to which it belongs. It is possible to run jobs on any cluster, but if you are unsure whether you should be using a particular group of machines please [[mailto:net@physics.umn.edu?subject=Condor Question|check first]].
<note>
You can see which servers belong to each cluster, and what their capabilities are, on the [[https://www.physics.umn.edu/resources/myphys/computing/systems.html|Linux Servers Listing]] page in MyPhys.

If your research group has no computational resources of its own, there is a general-purpose ''phys'' cluster which can be used by anyone.
</note>

You can also get an idea of activity within each cluster (although not directly condor-related) at our [[http://monitor.physics.umn.edu/ganglia/|Ganglia monitoring page]]
===== Lightning Condor Summary =====

Useful commands for submitting jobs are

    * ''condor_run'' - for quick & easy job submission
    * ''condor_submit'' - for full control

Useful commands for job and machine status are

    * ''condor_status'' shows active machines and queues
    * ''condor_status -submitters'' shows job submitter summary
    * ''condor_q'' shows jobs in the local job queue
    * ''condor_q -global'' shows jobs in the global job queue

You can find some more information at:

    * [[http://www.cs.wisc.edu/condor/manual/|Condor Manual]]
    * [[https://condor-wiki.cs.wisc.edu/index.cgi/wiki|Condor Wiki at UW Madison]]
    * [[http://research.cs.wisc.edu/condor/tutorials/fermi-2005/|Quick Condor Tutorial for Fermilab]]

===== Submitting batch jobs =====

==== Use vanilla environment ====

Unless you've specifically used ''condor_compile'' to build your programs, you'll need to submit your jobs in the "vanilla" universe.

  universe = vanilla
  
==== Limit email output ====

  Notification = error

==== Request slot resources ====

Almost all our condor slots are set up as "partitionable", which means you can request what resources are needed. Try to specify appropriate values in your submit file so that condor can reserve resources for your job (without this, your job will be given default values which may cause it to be held). For example:
  request_cpus = 1
  request_memory = 2048

==== think about your data access ====

Never use your home directory for job i/o - you should probably be using a ''/data'' volume.

===== Where do jobs run =====

By default, the cluster which executes a job is determined by the machine where you issue the ''condor_submit'' command - for example, if you submit a job from a CMS system, it will execute on the CMS cluster.

You can override this behavior in your submit file by manipulating the CondorGroup job ClassAd. For example, you could place the following line in your job file to make the jobs run on the CMS server farm:

  +CondorGroup = "cmsfarm"

In addition, you can let your jobs run on **any** cluster, with the condition that it will be pre-empted (ie killed) if a job with a higher rank (based on the group owning the cluster) needs to run. You can enable this behavior with:
  +CanEvict = True

===== Why won't my job run =====

Some commands to help analyze why your jobs isn't matching

  condor_q -analyze <jobid>
  condor_q -better <jobid>
  
Why is job not running on a particular machine
  condor_q -better <jobid> -machine <name>
  condor_q -better:reverse -machine <name>