7. Visual Studio Windows Azure Portal Rest APIs / PS Cmdlets US-North Central Region FC TOR PDU Servers TOR PDU Servers TOR PDU Servers TOR PDU Servers TOR PDU Servers TOR PDU Servers TOR PDU Servers TOR PDU Servers

8. Cluster 5 Cluster 4Cluster 3Cluster 2Cluster 1 TOR Agg PDU Agg Datacenter Routers TOR PDU TOR PDU TOR PDU TOR PDU TOR PDU TOR PDU TOR PDU TOR PDU TOR PDU TOR PDU TOR PDU TOR PDU TOR PDU TOR PDU … ……… … … Servers Agg Aggregation Routers and Load Balancers Cluster Network Aggregation Top of Rack Switches Racks Power Distribution Units

9. Cluster PDU AGG TOR Switch … PDU TOR Switch … … … PDU Cluster TOR Agg PDU TOR PDU TOR PDU … Servers Rack 1 Rack 2 Rack 20

10. Inside a Physical Server Physical Server Host Partition Trust boundary PDU TOR Switch … Unallocated CPUs VM PaaS VM Role Instance IaaS VM Role CPU

12. AGG TOR Switch PDU

13.  FC deploys the role instances in (at least) two different fault domains.  Different roles are allocated to fault domains independently  An even distribution is maintained when scaling up or down  No way to control the Fault Domain mapping, but it can be queried for each role instance:  Portal  REST service mgmt. APIs (“FaultDomain”)  Queuing can be defined between the layers (only LB by default)

14.  Update Domains (UD) control how to the service is updated.  A single UD is being updated for a role at a time.  Scenarios:  User Initiated: PaaS service owner updates the service package or chooses a different Guest OS  Platform Initiated: Update Guest OS for PaaS services when a new version is released (e.g. security fixes); Update the server (hypervisor)  Implementation Details:  Role instances are assigned into different UDs, circularly  Alignment between UDs of the different roles  Up to 20 UDs per Service (5 by default)

16. Web RoleFD0FD1 UD0IN_0 UD1IN_1 UD2IN_2 Worker RoleFD0FD1 UD0IN_0 UD1IN_1

18. Running Highly Available Cloud Virtual Machines

19. Sample application to demonstrate Windows Azure Usage (application migrated from customer premise). Sample application specifics: High redundancy for each component Load balancer for the front end Data layer can be implemented by SQL Server or SQL Azure (here); alternatively, can utilize Windows Azure storage Set up the whole application in the same affinity group to gain physical proximity

20. Availability sets instruct how to allocate VMs in the datacenters to isolate impact for hardware faults and infrastructure updates. Availability sets are defined through portal or REST APIs. Availability sets has to be defined for each redundant application tier to achieve 99.95% SLA We do not offer SLA unless there are 2 VM instances defined and used in each availability set Application SLA is compositional and dependent on the multiplication of the SLA components (each tier, compute, networking, etc) e.g. Front End may cause unavailability of the entire service. No correspondence between fault domains used in different availability sets Thus, queuing or load-balancing is being added between the availability sets

21. Scenario: Platform initiated update of the servers which run the IaaS VM instances. Goal: high redundancy for the IaaS service Each role is allocated to a different update domain (up to 5) When physical servers are updated, only fraction of the capacity will be touched at a time (or less). No mapping between update domains in different availability sets. IaaS service update is under the customer responsibility. In some cases customer VM update and infrastructure update can happen in the same time. IaaS update notifications are sent to avoid this. Hardware failures can occur any time. Thus, platform update + hardware failure could still cause service outage for dual VM availability sets.

25. Infrastructure Operations Impacting Customer Services

26. SymptomHealing Operation Potential Causes Issue with a customer code or customer VM Reboot the VM(s) Role instance or Guest OS crash (PaaS) Customer OS Crash (IaaS) Issue with physical server or rack Allocate the impacted customer VMs to the different server(s) Physical server software failure Physical server hardware failure Rack / PDU / ToR Failure

27. Note: your role instance keeps the same VM and VHDs, preserving cached data in the resource volume

28. AspectCloud Services (PaaS)Azure VMs (IaaS) Fault Domain countTwo per RoleTwo per Availability Set Update Domain countFive by default; up to twentyFive Platform updateUD by UD Administrator initiated update UD by UD, or Blast, or Customer Controlled UD walk or VIP-Swap Administrator controlled (can be automated using PowerShell or REST management APIs) Frontend and backend highly-available addressability Windows Azure provides Load-Balancer per role; queuing recommended for backend roles Administrator defines endpoints in VMs and maps them to a load-balanced set; queuing recommended for backend roles SLA99.95% uptime for roles with two or more role instances 99.95% uptime for Availability Sets with two or more VMs Multi-service collocationYes, using Affinity Groups UD/FD automated management when service grows / shrinks Yes (except when deleting a specific instance) Yes when service grows; no when shrinks