1. Predictable Computer Systems Remzi Arpaci-Dusseau University of Wisconsin, Madison

2. Trends

3. Complexity Cheap Components Everything Interconnected

4. Problems

5. Nothing Works As Expected Performance Fault-Tolerance Security

6. What Would Be Ideal

7. Ideal Assemble large-scale system from cheap, complex components System works in predictable manner

8. Key: How Components Interact

9. State of the Art APIs Protocols

10. Beyond APIs and Protocols: Understanding “Behavior”

11. A Small Example: Understanding the Failure Behavior of Local File Systems

12. Understanding FS Failure Type-aware fault injection Make fault injection layer aware of FS structures e.g., make an inode block fail Why useful Can infer how file system reacts to failures at different points in its code

13. Write Errors: Recovery Techniques Ext3, JFS don’t react to write failures ReiserFS (almost) always calls panic() Zero Stop Propagate Retry Redundancy Recovery Ext3ReiserFSJFS

14. What We Need

15. Vocabulary + Techniques + Tools Methods to = Understand Behavior Predictable -> Computer Systems

16. CSI: Computer Systems Investigation

17. ADvanced Systems Lab (ADSL) Gray-box Operating Systems and Storage Systems Andrea Arpaci-Dusseau Remzi Arpaci-Dusseau

18. ADvanced Systems Lab (ADSL) Who does the real work: Nitin Agrawal Lakshmi Bairavasundaram John Bent Nathan Burnett Tim Denehy Camille Fournier Haryadi Gunawi Todd Jones James Nugent Ina Popovici Vijayan Prabhakaran Muthian Sivathanu Who does the real work: Nitin Agrawal Lakshmi Bairavasundaram John Bent Nathan Burnett Tim Denehy Camille Fournier Haryadi Gunawi Todd Jones James Nugent Ina Popovici Vijayan Prabhakaran Muthian Sivathanu

20. Goal: Building Distributed Systems

21. Large-Scale Distributed Systems D D W W W Front Ends C C C DBMS Net Online StorageArchival Storage Internet Clients

22. Ideal: Legos Top Side What You See Is What You Get