Establishing%20an%20inter-organisational%20OGSA%20Grid:%20Lessons%20Learned

1
Establishing an inter-organisational OGSA Grid
Lessons Learned

• Wolfgang Emmerich
• London Software Systems, Dept. of Computer
  Science
• University College London
• Gower St, London WC1E 6BT, U.K
• http//www.sse.ucl.ac.uk/UK-OGSA

2
An Experimental UK OGSA Testbed

• Established 12/03-12/04
• Four nodes
• UCL (coordinator)
• NeSC
• NEReSC
• LeSC
• Deployed Globus Toolkit 3.2 throughout onto
• Heterogeneous HW/OS
• Linux
• Solaris
• Windows XP

3
Experience with GT3.2 Installation

• Different levels of experience within team
• Heterogeneity
• HW (Intel/SPARC)
• Operating system (Windows/Solaris/Linux)
• Servlet container (Tomcat/GT3 container)
• Interaction with previous GT versions
• Departure from web service standards prevented
  standard tool use
• JMeter
• Development environments (Eclipse)
• Exception management tools (Amberpoint)
• Interaction with system administration
• Platform dependencies

4
Performance and Scalability

• Developed GTMark
• Server-side load model SciMark 2.0
  (http//math.nist.gov/SciMark)
• Client-side load model, configuration and metrics
  collection based on J2EE benchmark StockOnline
• Configurable Benchmark
• Static vs dynamic discovery of nodes
• Loads for fixed period of time or until steady
  state obtained
• Constant or variation of concurrent requests

5
Performance Results
6
Scalability Results
7
Performance Results

• Performance and scalability of GT3.2 with
  Tomcat/Axis surprisingly good
• Performance overhead of security is negligible
• Good scalability - reached 96 of theoretical
  maximum
• Tomcat performs better than GT3.2 container on
  slow machines
• Surprising results on raw CPU performance

8
Reliability

• Tomcat more reliable than GT3.2 container.
• Tomcat container sustained 100 reliability under
  load
• GT3.2 container failed once every 300 invocations
  (99.67 reliability)
• Denial of Service Attack possible by
• Concurrently invoking operation on the same
  service instance (they are not thread safe!)
• Fully exhausting resources
• Problem of hosting more than one service in one
  container
• Trade-off between reliability and reuse of
  containers across multiple users/services.

9
Security

• Interesting effect of firewalls on testing and
  debugging
• Accountability and audit trails demand users be
  given individual accounts on each node
• Overhead of node and user certificates (they
  always expire at the wrong time)
• Current security model does not scale
• Assuming cost of 18/Admin hour
• 10 users per node (site)
• It will cost approx. 300,000 to set up a 100
  node grid with 1000 users
• It will be prohibitively expensive to scale up to
  1,000 nodes(with admin costs in excess of 6M)

10
Deployment

• How do admins get grid middleware deployed
  systematically onto grid nodes?
• How can users get the services onto remote hosts?
• We tried out SmartFrog (http//www.smartfrog.org)
• Worked very well inside a node.
• Impossible across organisations
• SmartFrog daemon would need to execute actions
  with root privileges which some site admins just
  did not agree to
• Security paramount (SmartFrog would be the
  perfect virus distribution engine)
• SmartFrogs security infastructure incompatible
  with GT 3.2 infrastructure

11
Looking Ahead

• Installation efforts need to be reduced
  significantly
• Binary distributions
• For a few selected HW/OS platforms
• Standards compliance
• Track standards by all means
• Otherwise no economies of scale
• Management console
• Add / remove grid hosts
• Need to be able to monitor status of grid
  resources
• Across organisational boundaries
• More lightweight security model needed
• Role-based Access Control
• Trust-delegation
• Deployment is a first-class citizen
• Avoid adding as an afterthought
• Needs to be built into middleware stack

12
Conclusions

• Very interesting experience
• Building a distributed system across
  organisational boundaries is different from
  building a system over a LAN
• Insights that might prove useful for
• OMII
• Globus
• ETF
• There is a lot more work to do before we realize
  the vision of the Grid!

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Acknowledgements

• A large number of people have helped with this
  project, including
• Dave Berry (NeSC)
• Paul Brebner (UCL, now CSIRO)
• Tom Jones (UCL, now Symantec)
• Oliver Malham (NeSC)
• David McBride (LeSC)
• Savas Parastatidis (NEReSC)
• Steven Newhouse (OMII)
• Jake Wu (NEReSC)
• For further details (including IGR) check out
  http//sse.cs.ucl.ac.uk/UK-OGSA