1. 1 Performability Models for Designing Disaster Tolerant Cloud Computing Systems

2. 2 Agenda Motivation Approach Architecture Perfomability Sensitivity Analysis Survivability Evaluation GeoClouds Tool

3. 3 MOTIVATION Why adopt cloud computing?

4. 4 Cloud computing infrastructure is available on demand. Adopted as a service. Minimizes the costs of IT infrastructures Service Level Agreement (SLA). Penalties may be applied if the defined availability level is not satisfied

5. 5 Motivation Large cloud service providers adopts service level agreements (SLAs) to regulate the availability of the cloud service. Costs Availability Performance (response time) Service provider needs to carry out availability analysis

6. 6 Motivation IaaS – computing resources in the form of virtual machines (VMs). Disasters Multiple data located in different geographical locations Availability improvement VM migration time increases due to distance between data centers

7. 7 APPROACH

8. 8 Evaluate dependability cloud computing systems deployed into geographically distributed data centers. (RBD - Reliability Block Diagrams) (SPN - Stochastic Petri Nets)

9. 9 ARCHITECTURE

10. 10 Architecture

11. 11 (SPN/RBD) BUILDING BLOCKS

12. 12 Hierarchical Modelling

13. 13 COMBINED MODEL

14. 14 Survivability Evaluation

15. 15 RTO and RPO Evaluation RTO Model RPO Model

16. 16 Results

17. 17 Sensitivity Analysis

18. 18 Results

19. 19 Results

20. 20 Geoclouds Modcs

21. 21 Validation

22. 22 Validation

23. 23 Conclusion Performability Survivability Tool Validation Sensitivity Analysis Next Steps : Write Papers

24. 24 Questions