SQL Server AlwaysOn for Dummies SQLSaturday #202 Edition
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The document discusses SQL Server AlwaysOn technologies, focusing on high availability solutions including AlwaysOn Availability Groups and AlwaysOn Failover Cluster Instances. It outlines the architecture, benefits, and complexities of each solution while emphasizing the foundational role of Windows Server Failover Clustering. The presentation also touches on installation, configuration, and operational considerations for managing these technologies effectively.
![AlwaysOn
Availability Groups
Database[s] Level High Availability](https://image.slidesharecdn.com/sqlserveralwaysonfordummiessqlsat202edition-130610074843-phpapp01/85/SQL-Server-AlwaysOn-for-Dummies-SQLSaturday-202-Edition-25-320.jpg)
SQL Server AlwaysOn for Dummies SQLSaturday #202 Edition
- 1. SQL Server AlwaysOn for Dummies Mark Broadbent Principal SQL Consultant SQLCloud SQLCLOUD.CO.UK
- 2. About Mark Broadbent “Possibly the hardest drinking DBA on the planet” “30 billion times more intelligent than a live mattress” Email: mark.broadbent@sqlcambs.org.uk Twitter: retracement Blog: http://tenbulls.co.uk PASS UK Regional Mentor Event Lead to the UK’s first ever SQLSaturday (Cambridge) Event #2nd due on Friday 27th Sept 2013 (pre-con) 28th Sept (Community day) http://www.sqlsaturday.com/228/eventhome.aspx Cambridgeshire PASS Chapter UG Leader http://sqlcambs.org.uk
- 3. SQLSaturday Cambridge 2013 27th (pre-con) and 28th (free) September http://www.sqlsaturday.com/228 Queen’s College, Cambridge CB3 9ET What is the air-speed velocity of an unladen swallow?
- 4. Agenda Windows Server Failover Clustering & Quorum AlwaysOn Availability Groups AlwaysOn Failover Clustered Instances Introduction to AlwaysOn 3 2 1 4
- 6. AlwaysOn Technologies*1 *1 According to my interpretation! AlwaysOn Availability Groups AlwaysOn Failover Clustered Instances Database Mirroring Scalable Shared Database Replication
- 7. “AlwAys On” isnae new!
- 8. Dr. Evil Senior Microsoft Windows Clustering Program Manager
- 9. Don’t let the terms confuse you! Cluster Node Cluster Server Node Server Cluster Group Role Service or Application Virtual Server Failover Cluster Clustered Instance SQL Server Server Resources (take your pick) Quorum Client Network Private Network Interconnect Internal Network Public Network... LAN SAN Shared Storage Disk Cluster Storage Active/Passive Single Instance Multi Instance N+n Cluster Majority Votes Availability Group Replica Readonly Replica
- 10. AlwaysOn Clustered Instances Provide… • Abstraction of SQL instance • High availability of Instance name • Instance and related services failover as a unit • Instance components such as jobs and logins not a consideration • Distributed Transaction Support BUT • Shared data with single point of failure per instance. • Complex to administrate
- 11. Availability Groups Provide… • Abstraction at the databases level • Failover as a single Unit • High availability of “Instance” (listener) name • All the benefits of DB Mirroring ….and less of the problems (FS is supported) BUT • Connected replicas are potentially single point of failure (i.e user error – deletion of records) • Complex (arguably less than FCI) to administrate • Instance level components not failed over –contained dbs partially come to the rescue • No Distributed Transaction support for failover
- 12. AlwaysOn is…
- 13. Windows Server Failover Clustering The foundation of AlwaysOn
- 14. “The Magic” of Clustering Clustered “Application” Cluster Nodes The “magic” of clustering is the ability for the cluster to ensure only one set of services, executables and resources are alive on one node for a clustered application at any one time. A clustered application will be installed onto each node
- 15. “The Magic” of Clustering Clustered “Application” Cluster Nodes failover
- 16. “The Magic” of Clustering Clustered “Application” Cluster Nodes failover
- 17. Storage Network Internal Network A Basic Windows Cluster Public (or Client) Network Shared (or Asymmetric) Storage Quorum The Cluster Group Cluster Node Cluster Service
- 19. Quorum Models Node majority (no witness) Node majority with witness (disk or file share) No majority (disk witness only) +Node weighting Dynamic weighting -new to Windows 2012
- 20. DEMO Taking a look at our Cluster
- 21. AlwaysOn Failover Clustered Instances Instance Level High Availability
- 22. Installation Create and install your clustered instance on the first cluster node For all other nodes install executables on every other node
- 23. Clustered Instances Node A Node B SQL Server Instance A Role (formerly known as Cluster Group) Network Name
- 24. Clustered Instances failoverNode A Node B SQL Server Instance A Role (formerly known as Cluster Group) Network Name
- 25. AlwaysOn Availability Groups Database[s] Level High Availability
- 26. Availability Group consists of… Listener (Name and IP) Availability Group Resource Availability Group Databases SQL Instance Components Wndows Cluster Resources Replica/s Availability Cluster Group Mirroring Endpoints Availability Group Listener (Name and IP) Do not flippin’ touch!
- 27. Transaction Logs Secondary Replica SQL Server Instance A Transaction Logs Primary Replica SQL Server Instance A Availability Groups Transaction Logs Redo Sync/ Async Secondary Replica SQL Server Instance B Listener
- 28. Transaction Logs Secondary Replica SQL Server Instance A Availability Groups Transaction Logs Sync/ Async Secondary Replica SQL Server Instance B Listener Redo Transaction Logs Primary Replica SQL Server Instance B
- 29. Availability Groups and Readable Secondaries • 5 Replicas • 2 Synchronous, others Asynchronous • 1 Read-Write • 4 either Read-only, Read-Intent or No Access
- 31. ReadOnly Routing • Set connection string property ApplicationIntent=ReadOnly • Must connect to a listener. • Modify Secondary Replica Roles with read only routing url. • Modify Primary Replica Roles with read only routing list.
- 32. In Summary… • It is not all Butterflys and Unicorns so choose the HA solution appropriate to your requirements. • Failover Clustering is a very mature technology but requires specialist skill and understanding. It does not provide scalability. • Availability Groups partially rely on Windows Clustering but are slightly easier to setup and manage. They also provide reporting query scalability.
- 33. Tha mo bhàta-foluaimein loma-làn easgannan for attending this session and SQLSaturday #202 in Edinburgh Thank you!