Adjusting carbon topology to match high availability scenario requirements


Published on

High availability is a core enterprise requirement in any modern deployment. This ensures that systems can continue to function correctly even when there are failures. Ideally such systems should continue to function correctly and provide services while there are several failures.

Another important aspect is that system deployment architectures should ensure there are no single points of failure. Redundancy is the most widely used technique in designing such fault tolerant systems. This includes data redundancy, information redundancy, time redundancy etc. However, redundancy always comes at a cost and hence there is a cost vs. availability trade-off. Certain availability techniques may also result in performance overheads.

In this webinar, Afkham Azeez, Director of Architecture, will take a look at how these techniques are employed in the WSO2 platform to achieve high availability and fault tolerance, while taking the cost and performance factors into consideration. We will also look at some key aspects which will enable enterprise architects to make deployment topology decisions based on availability requirements at an optimum cost.

Published in: Technology
  • Be the first to comment

  • Be the first to like this

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide
  • Fox Mobile who ran for two years with zero downtime and multiple updates including a hardware refresh.
  • Membership modes – multicast & wkaA look at the cluster configuration
  • Availability Zones are distinct locations that are engineered to be insulated from failures in other Availability Zones and provide inexpensive, low latency network connectivity to other Availability Zones in the same Region. By launching instances in separate Availability Zones, you can protect your applications from failure of a single location. Regions consist of one or more Availability Zones, are geographically dispersed, and will be in separate geographic areas or countries. The Amazon EC2 Service Level Agreement commitment is 99.95% availability for each Amazon EC2 Region. Amazon EC2 is currently available in three Regions: the US East (Northern Virginia) Region and the US West (Northern California) Region in the United States, and the EU (Ireland) Region in Europe."
  • Adjusting carbon topology to match high availability scenario requirements

    1. 1. Adjusting Carbon Topology toMatch High Availability Scenario Requirements Afkham Azeez Director of Architecture WSO2 Inc 1
    2. 2. About Me• PMC member Apache Axis, Committer Synapse & Web Services• Member, Apache Software Foundation• Co-author, Axis2 Web Services• Director of Architecture, WSO2 Inc• Blog:• Twitter: afkham_azeez 2
    3. 3. Agenda• A brief look at the WSO2 platform• Carbon clustering for availability• Cost of availability & related topologies 3
    4. 4. WSO2 Offerings• WSO2 Carbon • Full platform of servers for deployment on-premise, in private or public cloud • Products share a consistent architecture and core platform services (e.g. logging, management, security, identity, caching) through OSGi and the “Carbon Core” • Includes ESB, AppServer, Data Services, Governance, Identity, Business Process, and more• WSO2 Stratos • Platform-as-a-Service (PaaS) Foundation • Supports running servers as elastic, metered, billed, multi-tenant with self-service • Including all Carbon Servers, PHP, Jetty, and a growing list through a standard Cartridge model• WSO2 StratosLive • • WSO2’s Public PaaS • An instance of Stratos running in the cloud with all Carbon Servers available 4
    5. 5. Consistent Architecture• Carbon: A consistent set of class-leading enterprise servers • The same products run either on-premise or in the cloud, single-tenant or multi- tenant • Utilize the same Carbon core runtime for a seamless experience• Stratos: A cloud platform for enterprise, hybrid and public deployment • Extends the deployment to support full self-service, elastic scaling, metering and billing • Supports Carbon and native server runtimes • Including Java and non-Java servers such as Jetty and PHP • Re-uses the same core Carbon architecture to offer core PaaS services including: • Identity, Logging, File, Relational Storage, Column Storage, Code Deployment, etc• Both projects share a common set of OSGi modules and a core runtime architecture 5
    6. 6. WSO2 SOA Platform 6
    7. 7. WSO2 Carbon 7
    8. 8. AvailabilityThe degree to which a system, subsystem, or equipment is in a specified operable and committable state at the start of a mission, when the mission is called for at an unknown, i.e., a random, time.Simply put, availability is the proportion of time a system is in a functioning condition. 8
    9. 9. Availability 9
    10. 10. Availability 10
    11. 11. High Availability (HA)A system that is designed for continuous operation in the event of a failure of one or more components. However, the system may display some degradation of service, but will continue to perform correctly.The proportion of time during which the service is accessible with reasonable response times should be close to 100%.All single points of failure should be eliminated 11
    12. 12. HA, CO & CA• Continuous Operation (CO) • Ability to avoid planned outages. • hardware and software maintenance carried out while applications remains available users.• Continuous Availability (CA) • Combines the characteristics of HA and CO to keep the applications running without any noticeable downtime • Hot update/ graceful round-robin restart 12
    13. 13. High Availability Techniques• Redundancy • Time – retransmit • Data – e.g. parity bits • Processing – e.g. redundant nodes• Diversity • e.g. Hybrid deployments, do the same thing using different implementations 13
    14. 14. How to decide required availability?• Average throughput (TPS)• Max throughput (TPS)• Monetary value of a transaction• Average loss & max loss per second of downtime• Decide on how much to invest on availability based on cost vs. benefit tradeoff 14
    15. 15. Patching Production Deployments Patch Distribution Coordinator 1. Check patch list 2.Pull new patch 3. Push patch 3. Push patch 3. Push patch 3. Push patch 15
    16. 16. Patching Production Deployments Patch Distribution Coordinator Round-robin 4. Maintenance mode 5. Graceful restart 16
    17. 17. Clustering• Clustering for scalability• Clustering for availability 17
    18. 18. Clustering for scalability 18
    19. 19. Clustering for availability Group Communication Channel/State replication 19
    20. 20. Carbon Clustering• Membership types • Static • Dynamic • Hybrid• Membership modes • Multicast • Well-known address 20
    21. 21. Static membership• Predefined members• Other (non-predefined) nodes cannot join Static group M1 M2 N M3 M4 21
    22. 22. Dynamic membership• No predefined members• Nodes can join & leave Dynamic group M1 M2 N Join M3 M4 22
    23. 23. Hybrid membership• Some predefined (well-known) members, and some dynamic members• Nodes can join & leave• Membership revolves around the static members Hybrid group Dynamic members Static members N Join M5 M6 M1 M2 (IP, Port) M7 M3 M4 23
    24. 24. Multicast based membership management M4 M1 N Join (IP, Port) M2 M3 24
    25. 25. Well-known Address (WKA) based membership managementHybrid group Dynamic members Static members M6 M5 WK1 N WK2 Notify Join (IP, Port) M7 WK3 WK4 25
    26. 26. Multicast vs. WKAMulticast WKAAll nodes should be in the same subnet Nodes can be in different networksAll nodes should be in the same multicastdomain No multicasting requirementMulticasting should not be blockedNo fixed IP addresses or hosts required At least one well-known IP address or host requiredFailure of any member does not affect New members can join with some WKAmembership discovery nodes down, but not if all WKA nodes are downDoes not work on IaaSs such as Amazon IaaS-friendlyEC2 Requires keepalived, elastic IPs or some other mechanism for remapping IP addresses of WK members in cases of failure 26
    27. 27. Multicast vs. WKA – how to decide?• Multicast • Cluster is going to be setup in a network where multicasting is allowed• WKA • Cloud based deployment • Members are distributed across datacenters & regions • Multicasting blocked 27
    28. 28. HTTP Session Replication• catalina-server.xml • <Cluster className="org.wso2.carbon.core.session.CarbonTomcatSimpleTcpCluster"/> • <Valve className="org.wso2.carbon.tomcat.ext.valves.CarbonTomcatSessionReplicationValve"/>• web.xml • <distributable/> 28
    29. 29. State ReplicationJSR-107/JCache A standard Java Caching API for use by developers and a standard SPI ("Service Provider Interface") for use by implementers. import javax.cache.* … CacheManager cacheMgr = Caching.getCacheManager(); Cache<String, Integer> cache =cacheMgr .getCache(cacheName); cache.put(“key”, sampleValue); Integer i = cache.get(“key”); 29
    30. 30. State ReplicationCarbonContext based API Cache cache = CarbonContext.getCurrentContext().getCache(); cache.put(“key”, sampleValue); Integer i = cache.get(“key”);Axis2 Contexts Using Axis2 clustering StateManager – axis2.xml <stateManager class="org.apache.axis2.clustering.state.DefaultStateManager” enable=”true"> 30
    31. 31. Elastic Load Balancer 2.0• New sysadmin-friendly configuration language• High performance PassThrough transport• Tenant-aware load balancing• Ability to dedicate clusters for tenants (private jet mode)• Improved auto-scaler • Separate IaaS-aware Cloud controller takes care of spawning new instances on different IaaSs 31
    32. 32. Tenant-aware LB 32
    33. 33. Private Jet mode• Analogy • Economy class • no SLA management, only elasticity • Business class • elasticity plus SLA guarantees • Private Jet • Guaranteed isolated VMs or machines for a specific tenant • Still elastically scaled
    34. 34. Private Jet Mode 34
    35. 35. Topologies• Single node• Multi-node with LB• Multi-node with elasticity using ELB• Management & worker node separated• Multi-zone or multi-datacenter deployment• Multi-region 35
    36. 36. Single nodeHIGHEST Availability CostLOWEST 36
    37. 37. Primary-secondaryHIGHEST Availability CostLOWEST Primary Secondary 37
    38. 38. Primary-secondary, multiple LBHIGHEST keepalived Availability CostLOWEST Primary Secondary 38
    39. 39. Active cluster, multiple LBHIGHEST keepalived Availability CostLOWEST Active Active Active 39
    40. 40. Management & Worker Node Separation• Proper separation of concerns - management nodes specialize in management of the setup while worker nodes specialize in serving requests to deployment artifacts• Only management nodes are authorized to add new artifacts into the system or make configuration changes• Worker nodes can only deploy artifacts & read configuration• Lower memory foot in the worker nodes because the management console related OSGi bundles are not loaded• Improved security - management nodes can be behind the internal firewall & be exposed to clients running within the organization only, while worker nodes can be exposed to external clients.• Isolation of failures 40
    41. 41. Management & Worker Node SeparationHIGHEST Availability CostLOWEST 41
    42. 42. Regions & Zones 42
    43. 43. Stratos 2.0 Architecture 43
    44. 44. Multi-zone or multi-datacenter DeploymentHIGHEST Cloud Controller Zone 1 Zone 2 Availability Region X CostLOWEST 44
    45. 45. Multi-region deploymentHIGHEST Zone 1 Zone 2 Region X Zone 1 Availability Zone 2 CostLOWEST Region Y 45
    46. 46. Multi-IaaS Deployment Cloud Controller 46
    47. 47. Multiple IaaS (hybrid) DeploymentHIGHEST Zone 1 Private cloud (data center) Zone 2 Zone 1 Zone 2 Amazon EC2 Zone 1 Availability Cost Zone 2LOWEST Rackspace Cloud 47
    48. 48. Single Node Primary-Secondary, single LB Primary-Secondary, with multiple LBs Multi-node active cluster - Single zone Cost of Availability Multi-zone Multi-region Multi-IaaS48
    49. 49. HA for the Load Balancer• Load balancer cluster• Keepalived• Elastic IP address• Round Robin DNS 49
    50. 50. Monitoring Servers• Monit • Automatically provide alerts & restart processes when monitored items (e.g. latency) fall below certain thresholds.• New Relic• Nagios 50
    51. 51. ReferencesInformation on tenant-aware load balancing Stratos 51
    52. 52. Auto-scaler service deployment service failover for WSO2 ELB 52
    53. 53. Questions? 53