Resource and Test Management in Grids

1. Resource and Test Management in Grids Dick Epema, Catalin Dumitrescu, Hashim Mohamed, Alexandru Iosup, Ozan Sonmez Parallel and Distributed Systems GroupDelft University of Technology Rapid Prototyping in e-Science VL-e Workshop, Amsterdam, NL

2. A Brief Introduction to Grid Computing • Typical grid environmente.g., the DAS • Applications [!] • Resources • Compute (Clusters) • Storage • (Dedicated) Network • Virtual Organizations, Projects (e.g., VL-e), Groups, Users • Grids vs. (traditional)parallel production environments • Dynamic • Heterogeneous • Very large-scale (world) • No central administration →Most problems are NP-hard,need experimental validation

3. Outline • A Brief Introduction to Grid Computing • Koala: Processor and Data Co-Allocation in Grids • The Co-Allocation Problem in Grids • The Koala Design • Koala and the DAS Community • The Future of Koala • GrenchMark: Analyzing, Testing, and Comparing Grids • Grid Performance Evaluation Issues • The GrenchMark Architecture • Experience with GrenchMark • Take home message

4. The Co-allocation Problem in Grids (1)Motivation • Co-allocation = the simultaneous allocation of resources in multiple clusters to single applications which consist of multiple components • Reasons • Use more resources than available at single cluster at given time • Create a specific virtual environment (e.g., visualization cluster , geographically spread data) • Achieve reliability through replication on multiple clusters • Avoid resource contention on the same site (e.g., batches)

5. The Co-allocation Problem in Grids (2) Overall Example global queue KOALA local queues with local schedulers load sharing LS LS LS co-allocation clusters global job local jobs Source: Dick Epema

6. The Co-allocation Problem in Grids (3)Details: Processors and Data Co-Alloc. • Jobs have access to processors and data from many sites • Files stored at different file sites, replicas may exist • Scheduler decides on job component placement at execution sites • Jobs can be of high or low priority Source: Hashim Mohamed

7. The Co-allocation Problem in Grids (4)Details: Co-Allocated Job Types fixed jobs non-fixed jobs Job component size and placement fixed by user Job component size fixed by user, placement by scheduler decision semi-fixed jobs flexible jobs Job component size and placement by scheduler decision / fixed by user Job component size and placement by scheduler decision

8. The Koala Design Source: Hashim Mohamed SelectionPlacing job components ControlTransfer executable and input files InstantiationClaiming resources selected for each job component RunSubmit, then monitor job execution(fault-tolerance)

9. The Koala Selection StepMany Placement Policies • Originally supported co-allocation policies: • Worst-Fit: balance job components across sites • Close-to-Files: take into account the locations of input files to minimize transfer times • (Flexible) Cluster Minimization: mitigate inter-cluster communication; can also split the job automatically • But, different application types require different ways of component placement • So: • Modular structure with pluggable policies • Take into account internal structure of applications

10. The Koala Selection StepHOCs: Exploiting Application Structure • Higher-Order Components: • Pre-packaged software components with generic patterns of parallel behavior • Patterns: master-worker, pipelines, wavefront • Benefits: • Facilitates parallel programming in grids • Enables user-transparent scheduling in grids • Most important additional middleware: • Translation layer that builds a performance model from the HOC patterns and the user-supplied application parameters • Supported by KOALA (with Univ. of Münster) • Initial results: up to 50% reduction in runtimes

11. runner The Koala Instantiation StepThe Runners • Problem: How to support many application types, each with specific (and difficult) requirements? • Solution: runners (=interface modules) • Currently supported: • Any type of single-component job • MPI/DUROC jobs • Ibis jobs • HOC applications • API for extensions: write your own!

12. Koala and the DAS Community • Extensive experience gathered while assessing various co-allocation policies: over 25,000 completed jobs! • Koala has been released on the DAS in Sep 2005 [ www.st.ewi.tudelft.nl/koala/] • Hands-on Tutorials (last in Spring 2006) • Documentation (web-site) • Papers • IEEE Cluster’04, Dagstuhl FGG’04, EGC’05, IEEE CCGrid’05, IEEE Cluster’06, etc. • Koala helps you get results: • IEEE CCGrid’06, others submitted

13. The Future of Koala • Support for more applications types, e.g., • Workflows, Parameter sweep applications • Scheduling your application? • Communication-aware and application-aware scheduling policies: • Take into account the communication pattern of applications when co-allocating • Also schedule bandwidth (in DAS3) • Support heterogeneity • DAS3 • DAS2 + DAS3 • DAS3 + Grid’5000 + RoGRID • Peer-to-peer structure instead of hierarchical grid scheduler

14. Outline • A Brief Introduction to Grid Computing • Koala: Processor and Data Co-Allocation in Grids • The Co-Allocation Problem in Grids • The Koala Design • Koala and the DAS Community • The Future of Koala • GrenchMark: Analyzing, Testing, and Comparing Grids • Grid Performance Evaluation Issues • The GrenchMark Architecture • GrenchMark and the DAS Community • Take home message

15. Grid Performance Evaluation Current Practice • Performance Indicators • Define my own metrics, or use U and AWT/ART, or both • Workload Structure • Run my own workload; Mostly all users are created equal assumption (unrealistic) • Do not make comparisons (incompatible workloads) • No repeatability of results (e.g., background load) Need a common performance evaluation framework for Grid:GrenchMark

16. GrenchMark: a Framework for Analyzing, Testing, and Comparing grids • What’s in a name?grid benchmark→ working towards a generic tool for the whole community: help standardizing the testing procedures, but benchmarks are too early; we use synthetic grid workloads instead • What’s it about?A systematic approach to analyzing, testing, and comparing grid settings, based on synthetic workloads • A set of metrics and workload units for analyzing grid settings [JSSPP’06] • A set of representative grid applications • Both real and synthetic • Easy-to-use tools to create synthetic grid workloads • Flexible, extensible framework

17. GrenchMark Overview: Easy to Generate and Run Synthetic Workloads

18. Workload structure User-defined and statistical models Dynamic jobs arrival Burstiness and self-similarity Feedback, background load Machine usage assumptions Users, VOs Metrics A(W) Run/Wait/Resp. Time Efficiency, MakeSpan Failure rate [!] (Grid) notions Co-allocation, interactive jobs, malleable, moldable, … Measurement methods Long workloads Saturated / non-saturated system Start-up, production, and cool-down scenarios Scaling workload to system Applications Synthetic Real Workload definition language Base language layer Extended language layer Other Can use thesame workload for both simulations and real environments … but More Complicated Than You Think

19. GrenchMark and the DAS community • Generic Performance Evaluation [IEEE CCGrid’06] • Grid System Analysis • Performance testing, What-if analysis • Functionality Testing in Grid Environments • System functionality testing, Periodic testing • Comparing Grid Settings • Single site vs. co-allocated jobs • Releasing the Koala Grid Scheduler on the DAS • 5,000+ jobs successfully run (in all workloads); • Functionality tests for 3 different job submission modules • GrenchMark has been released in Nov 2005 [ grenchmark.st.ewi.tudelft.nl]

20. Take home message • PDS Group/TU Delft - resource and test management in Grid systems • Koala: Processor and Data Co-Allocation in Grids [ www.st.ewi.tudelft.nl/koala/] - Grid scheduling with co-allocation and fault-tolerance- many placement policies available- extensible runners system- easy-to-use, flexible- tutorials, on-line documentation, papers • GrenchMark: Analyzing, Testing, and Comparing Grids[ grenchmark.st.ewi.tudelft.nl]- generic tool for the whole community- generates diverse grid workloads- easy-to-use, flexible, portable, extensible, …

21. Thank you! Questions? Remarks? Observations? All welcome! www.st.ewi.tudelft.nl/koala grenchmark.st.ewi.tudelft.nl/