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Sql Server 2012 HA and DR -- SQL Saturday Richmond

Presented to SQL Saturday Richmond Virginia on 09-Mar-2013

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Sql Server 2012 HA and DR -- SQL Saturday Richmond

  1. 1. SQL Server 2012High Availability andDisaster RecoverySQL Saturday #187March 9, 2013Richmond, VAJoey D’Antoni
  2. 2. @jdanton  jdanton1@yahoo.comAbout Me Resources from Today’s Presentation 
  3. 3. Disaster Recovery—It’s All About Risk Management Understanding High AvailabilityToday’sPresentation Ok, I get that, now how do I protect my databases? Understanding Availability Groups
  4. 4. DisasterRecovery
  5. 5.  Recovery Time Objective – How long can your systems be down before your business is impacted?Disaster  Recovery Point Objective—How much data canRecovery your business lose before being impacted?Terms  These will vary highly by your industry, and your business model, but they apply to every application
  6. 6. "How fast do you want to go? How much do you want to spend?“ –attribution unknownRiskManagement
  7. 7.  In a nutshell, preparing a DR policy is just like buying insurance  Based on your firms tolerance for risk, business model, and geography  Extremely high levels of availability andRisk protection are available, at a very expensiveManagement cost  Very reasonable levels of protection and availability can be had at a low cost  If you use a cloud provider—you still need to think about this!
  8. 8. AlwaysOn Availability Groups Database MirroringDR Solutions in Log ShippingSQL Server Multi-site Replication Multi-site Clustering Virtualization Multi-site failover
  9. 9. HighAvailability
  10. 10. High availability is a system design approach and associated service implementation that ensures a prearranged level of operational performance will be met during a contractual measurement period. --wikipediaHigh • System Design allows for minimal downtime in the event ofAvailability hardware and operating system failures
  11. 11.  SQL Server Failover Cluster InstancesHigh  VMWare vMotion/Hyper-V Live MigrationAvailability in  Both of these technologies have a single pointSQL Server of failure in shared storage
  12. 12. Review  AlwaysOn Availability Groups  Database MirroringSQL Server HA  Failover Cluster Instancesand DR  Log ShippingOptions  Replication
  13. 13. • Transaction Log Backups take place on primary • External Process ships logs to secondary server(s) Secondary • Data can be read on secondary Server (except during t-log apply) DB (S) PrimaryLog Shipping Server DB (P) Secondary Server Log DB Backup (S) Optional
  14. 14. Pros • Standard Edition • Supports Multiple Targets • Can Read Secondary CopiesLog ShippingPros/Cons Cons • Dependent on Backup on Primary • Manual Failover Process • Reasonably High Complexity
  15. 15. • This is a really high level view of replication • There are numerous topologies and options involved in replication • This is the nuts and bolts of itReplication Image Credit—MS Books Online
  16. 16. Pros • Can Replicate to Multiple Servers • Replicate subset of data • Standard Edition (transactional)ReplicationPros/Cons Cons • Manual Failover • Unknown RPO • Can be fragile • Re-sync process can be ugly • Also requires connection change for failover
  17. 17. Cluster Virtual NameInstanceNameFailover SQL InstanceClusterInstances Node A Node B Windows Failover Cluster
  18. 18. Shared Storage (SAN or SMB Share*) Windows Cluster (Windows Server 2012Failover Standard Edition)Cluster SQL Server Standard Edition (Two NodeInstances Limit)Requirements Cluster Network Quorum Disk
  19. 19. Pros • Connections are transparent • Failover is automatic • Allows for whole instance protectionSQL Server • Multiple servers can be involvedFailoverClusterInstances ConsPros/Cons • Setup is complex • Hardware can sit idle in some configs • Single storage doesn’t allow for data protection* *More on this later
  20. 20. • Database transactions are compressed and shipped to secondary server (2008+) • The optional witness server facilitates automatic failover • Transfer may be sync or async*Database Primary Secondary Server ServerMirroring Mirror Mirror DB DB Witness Server *Enterprise Edition Only
  21. 21. Pros • Automatic Failover (w/witness) • Configuration is fast and easy • Failover happens quickly • Corrupted pages get fixed on secondaryDatabaseMirroringPros/Cons Cons • Is per database—multiple DB failovers need scripting • Async only available in EE • Marked as deprecated in SQL 2012 • Secondaries are inaccessible (except for snapshots)
  22. 22. Instance Instance 1 2 AG AG (P) (S)AlwaysOn Node A Node BAvailabilityGroups Washington Chicago Listener Name (AD VCO) Windows Cluster
  23. 23.  Requires SQL Server Enterprise Edition  Windows Cluster  All servers in same Windows Domain  Databases Failover as a groupAlwaysOn  No Shared Storage NeededAvailability  Async and Sync ModesGroups  Automatic and Manual Failover  Supports up to 4 replica copies  Replicas can be read  Backups on secondary copies
  24. 24. Pros • Readable secondaries allow for load distribution • No shared storage can reduce hardware costs • Multiple databases failing together is great for complexAlwaysOn apps • Connection string handledAvailability gracefully by listenerGroups • Administration all through SSMS ConsPros/Cons • Config is easy • Large topologies lead to $$$ license costs • Enterprise Edition only • New feature, so some growing pains • Changes in application code needed
  25. 25.  Can cluster using SMB shares—becomes more viable option with SMB 3.0 in Windows Server 2012SQL 2012  Failover Process is changed—isAlive and LooksAlive go away. Replaced withWhat’s New sp_server_diagnostics(Clustering)  Multi-subnet clustering is now available—this is designed for stretch clustering using SAN replication
  26. 26. Availability GroupsSQL Server Mirroring is marked as deprecated  Not sure the long term impact of this for2012 DR New standard edition and DRFeatures No real changes to replication or log shipping
  27. 27. WindowsServer 2012
  28. 28.  Great concept—allows for clusters to be automatically rebootedWindows  Works perfectly with SQL Server FailoverServer 2012 Cluster InstancesCluster Aware  Doesn’t work with AlwaysOn AvailabilityUpdating Groups, at the moment
  29. 29. Quorum
  30. 30. Windows Cluster Q Node 1 Node 2Quorum Node Majority Mode Node and Disk Majority In Node/Disk Majority Mode Cluster sustain node failure
  31. 31. AlwaysOnAvailability DemoGroups
  32. 32. Understand your business need before designing a HA and DR strategy DR is just like buying insurance—youSummary don’t need it until you do. Lots of good options for HA and DR in SQL Server for many price points Always have a plan!
  33. 33. Questions
  34. 34. @jdanton – Twitter  – EmailContact Info  – Blog Resources from today: