Experiences through Grid Challenge Event

1
Experiences through Grid Challenge Event

• Yoshio Tanaka

2
Grid Challenge

• A competition for programming on a Grid
• Main objectives
• For participants
• To provide opportunities to use real Grid (for
  participants)
• For us
• To understand obstacles/problems to make a Grid
  production level (1000cpus are shared by many
  users)
• To have an opportunity to encourage participants
  to use our software (e.g. Ninf-G, GXP)
• 30 students/graduates were participated in this
  event
• Provide 960cpus testbed for participants
• Schedule
• Preliminary Feb. 1 Feb. 28
• Final round Mar. 5 Mar. 20

3
Grid Challenge

• Two categories
• Regular routine
• A problem is provided
• Graphic image analysis
• count the number of objects
• Ranked by the performance, i.e. which is the
  fastest program?
• Free routine
• Can do anything interesting
• Could have experiences on running his own
  software on real Grid

4
Software

• Software provided by the organizer
• ssh
• GXP
• GT2 batch jobmanager
• MPICH (p4)
• Ninf-G2
• Other software can be installed by participants

5
Contributed resources
Sites nodes/cpus IP addresses Administrated by
TITECH / Matsuoka 100/200 Public Tanaka-san
TITECH / Aida 30/60 Private Prof. Aida students
Tokushima U. 50/100 Private Prof. Ono students
U. Tsukua 20/40 Public students
UEC 50/100 Private AIST Support
U. Tokyo 40/40 Public AIST Support
U. Tokyo 63/126 Private AIST Support
U. Tokyo 107/214 Public AIST Support
AIST 40/80 public AIST Support
Total 500/960
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Preparation ( Feb. 1)

• Administrators installed software in every site
• Participants sent ssh public key
• Administrators created accounts for all
  participants
• Participants tested each cluster
• login
• compile
• test run
• Participants obtained Globus certificates from
  AIST GTRC CA (if necessary)
• Participants sent Subject DN and administrators
  added their entries to grid-mapfile

7
Preparation ( Feb. 1) (contd)

• AIST provided
• A document for obtaining Globus certificate
• Test script for Globus
• A how-to document and sample programs of
  Ninf-G2
• How to develop Ninf-G apps step-by-step
• Obtain certificate
• Test globus
• Develop and run Ninf-G apps
• client configuration file for the Grid challenge
  environment

8
Problems

• 30 participants shared 960 cpus for one month
• Some used ssh for process invocation
• Some used GXP for process invocation
• Some used Ninf-G2 for process invocation
• Need to take care (many) trouble shooting
• Some nodes went down
• pbs daemon died
• students usually made experiments in midnight
• Interactive use of backend nodes (via ssh/GXP)
  was allowed
• F32 prohibits interactive use
• AIST could not provide F32

9
Problems (contd)

• Participants expected that all processes would be
  launched immediately (co-allocation)
• ssh/GXP enables it
• Ninf-G2 could not expect
• In order to keep fairness, we decided to change
  the configuration of batch queuing system
• For each processor, set the max number of
  processes per user to 1
• Increased the max number of processes per
  processor to the number of participants (30)
• This is an unusual configuration!!

10
Insights valuable for PRAGMA

• Mixture of batch and interactive use introduce a
  problem
• batch is expected to provide
• dedicated environment
• load balancing
• Interactive use (via ssh) may disturb batch
• But some middleware/apps require interactive use
• co-allocation / grid-level scheduler is hard to
  solve
• (basically) Applications should not expect all
  resources are available
• Application developers need extra work for this
  feature
• Possible solutions
• Make application capable for using only available
  resources in as-is strategy
• Implement co-allocation based on reservation
• No grid-level reservation system yet
• Should be done manually
• Do we have the same problem in PRAGMA
  routine-basis experiments?