Sqlserveralwaysonfordummiessqlsantaedition 121218144206-phpapp02


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Sqlserveralwaysonfordummiessqlsantaedition 121218144206-phpapp02

  1. 1. SQL Server AlwaysOn for Dummies Mark Broadbent SQLCloud SQLCLOUD.CO.UK
  2. 2. Agenda 2 Windows Server Failover Clustering 3 AlwaysOn Failover Clustered Instances 1 Introduction to AlwaysOn 4 AlwaysOn Availability Groups
  3. 3. About Mark Broadbent “30 billion times more intelligent than a live mattress” • Email: mark.broadbent@sqlcambs.org.uk • Twitter: retracement • Blog: http://tenbulls.co.uk • Event Lead to the UK’s first ever SQLSaturday (Cambridge) http://www.sqlsaturday.com/events.aspx • Cambridgeshire PASS Chapter UG Leader http://sqlcambs.org.uk
  4. 4. Introduction to AlwaysOn
  5. 5. AlwaysOn Technologies*1 Replication Scalable Shared Database Database Mirroring AlwaysOn Failover Clustered Instances AlwaysOn Availability Groups *1 According to my interpretation!
  6. 6. AlwaysOn is…
  7. 7. 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 BUT • Shared data with single point of failure per instance. • Complex to administrate
  8. 8. 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
  9. 9. Dr. Evil Senior Microsoft Windows Clustering Program Manager
  10. 10. Don’t let the terms confuse you! Private Network Interconnect Active/Passive Single Instance Internal Network Multi Instance N+n Cluster LAN Client Network Cluster Node Cluster Server Node Server Public Network... Resources (take your pick) Cluster Group Role Clustered Instance Failover Cluster SQL Server Server Virtual Server Service or Application Disk SAN Cluster Storage Shared Storage Votes Quorum Majority
  11. 11. Windows Server Failover Clustering
  12. 12. “The Magic” of Clustering Cluster Nodes failover Clustered “Application”
  13. 13. “The Magic” of Clustering Cluster Nodes failover Clustered “Application”
  14. 14. “The Magic” of Clustering Cluster Nodes Clustered “Application”
  15. 15. A Basic Windows Cluster The Cluster Group Quorum Cluster Service Cluster Node Public (or Client) Network Shared (or Asymmetric) Storage Internal Network Storage Network
  16. 16. Understanding Quorum I’m Alive!
  17. 17. Quorum Models No majority (disk witness only) Node majority (no witness) +Node weighting Dynamic weighting -new to Windows 2012 Node majority with witness (disk or file share)
  18. 18. Taking a look at our Cluster DEMO
  19. 19. AlwaysOn Failover Clustered Instances
  20. 20. Installation
  21. 21. Clustered Instances Node A failover Network Name Role (formerly known as Cluster Group) SQL Server Instance A Node B
  22. 22. Clustered Instances Node A Node B Network Name Role (formerly known as Cluster Group) SQL Server Instance A
  23. 23. AlwaysOn Availability Groups
  24. 24. Availability Group consists of… Replica/s Listener Availability Group Databases Availability Group Resource Instance Components Cluster Resources
  25. 25. Availability Groups Listener SQL Server Instance B SQL Server Instance A Availability Group Secondary Replica Redo Transaction Logs Transaction Logs Sync/ Async
  26. 26. Readible Secondaries • • • • 5 replicas 2 synchronous, others aysnchronous 1 Read/ Write 4 either Readonly, Read-Intent or No Access
  27. 27. 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.
  28. 28. Using AlwaysOn DEMO
  29. 29. Installing to Server Core
  30. 30. [Session Code]
  31. 31. 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.