Mahesh Krishnan Architecting highly resilient applications on Azure ARC42 7

What comes out of the box? Multiple instances of services Elasticity on demand Storage redundancy (local or geo) Queue based decoupling Database replication Distributed caching Traffic Manager for location transparency Automation and Scripting Infrastructure Diagnostics and Telemetry

CharacteristicsStatistics workload Live scores workload Relevance of information PermanentTemporary Variations in loadMinor variations over time Spike during matches; “0” at other times Impact of temporary failure Amortized ImpactMajor impact during games Fallback StrategyDegrade to stale data ???

Modelling Availability Establish SLAs based on Workload and Lifecycle model Availability %Downtime/yearDowntime/month 90% - One nine36.5 days72 hours 99% - Two nines3.65 days7.2 hours 99.9% - Three nines~8 hours 45 minutes~43 minutes 99.95%~4 hours 22 minutes~22 minutes 99.99% - Four nines~52 minutes~4 minutes

Patterns for building the application Resiliency patterns Redundancy patterns Recovery patterns

Resiliency pattern – Async everything

Resiliency patterns for handling errors Try, Try Again Ignore the failure Fake it! Deny the request Go to Plan B

Resiliency pattern – Circuit breakers

Redundancy patterns Multiple copies within the same DC Multiple redundancies across multiple DCs Multiple redundancies across multiple providers

Recovery patterns Backup/Restore Idempotency considerations Compensators

Considerations Automate all the things Measure all the things Monitor all the things

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