Basic Grid Projects –
Condor (Part I)
Sathish Vadhiyar
Sources/Credits: Condor Project web pages
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
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
Condor Architecture – daemons /
processes
master
Startd
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Represents a machine to the Condor pool
Implement owner’s access control policies
Starts, stops, suspends jobs
Runs on executing machines
Starter
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Spawned by startd for a job
Coordinates with the job
Condor Architecture - daemons
Schedd
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Represents jobs to the condor pool
Maintain persistent queues of user’s requests
Runs on submit machines
Shadow
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Similar to starter functionality, but runs on submit machine
Job specific
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Collector
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Manager
Collects machine and resource information from all other daemons
Answers queries
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Negotiator
Retrieves information from collector
Does match making
Job Submission Steps
Idle capacity utilization
When owner returns,
Condor checkpoints
and migrates jobs
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
Steps
Step 1 – entities express
their characteristics through
classads
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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
ClassAds
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
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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
Examples
Examples