1. Basic Grid Projects – Condor (Part I)
Sathish Vadhiyar
Sources/Credits: Condor Project web pages

2. Condor Motivation
Most of the cycles (70%) of workstation pools are underutilized
High throughput computing – Large amounts of processing capacity over long periods of time
In contrast to High Performance Computing
Support system with distributed ownerships
Owners specify access policies

3. Condor Features Specialized workload management system
Provides a job queueing mechanism, scheduling policy, resource monitoring, and resource management
Can effectively harness wasted CPU power from otherwise idle desktop workstations
Can checkpoint and migrate a job to a different machine

4. Condor Architecture – daemons / processes
master
Startd
Represents a machine to the Condor pool
Implement owner’s access control policies
Starts, stops, suspends jobs
Runs on executing machines
Starter
Spawned by startd for a job
Coordinates with the job

5. Condor Architecture - daemons
Schedd
Represents jobs to the condor pool
Maintain persistent queues of user’s requests
Runs on submit machines
Shadow
Similar to starter functionality, but runs on submit machine
Job specific
Manager
Collector
Collects machine and resource information from all other daemons
Answers queries
Negotiator
Retrieves information from collector
Does match making

8. Job Submission Steps

9. Idle capacity utilization
When owner returns, Condor checkpoints and migrates jobs

10. classads Language used in Condor
For describing jobs, workstations, and other resources
Mapping from attribute names to expressions
Used by condor central manager to decide on job scheduling

11. Steps Step 1 – entities express their characteristics through classads
Also expresses constraints for other entities to follow
Also specifies ranks (preferences) to break ties in case there are more than one entities following the constraints.
Step 2 – matchmaker matches different classads
Step 3 – match maker notifies matched entities
Step 4 – matched entities establish allocation

12. ClassAds

13. More on ClassAds
Resource owners and customers can dynamically define own models – suitable for distributed setting
Matching and claiming as 2 distinct operations
5 components of matchmaking protocol
classAd specification
advertising protocol
matchmaking algorithm
matchmaking protocol
claiming protocol
Constraints, i.e. queries, may be expressed as attributes of classAd
classAd definition – mapping from attribute names to expressions

14. Examples

15. Examples