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Sql server 2012 ha dr nova

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My presentation on SQL Server 2012 HA and DR options, presented to the Northern Virginia SQL Server Users Group on 23 Jan 2012.

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Sql server 2012 ha dr nova

  1. 1. SQL Server 2012High Availabilityand DRNorthern Virginia SQL UsersGroup23-January-2012
  2. 2. About Me @jdanton on Twitter Joedantoni.wordpress.com Videos and Blogs at SSWUG.org Vice President of the Philadelphia SQL Server UG
  3. 3. Agenda Licensing Changes SQL Server 2008 to 2012—What’s Changed in HA and DR Geo-Clustering All about Availability Groups
  4. 4. Learning Objectives SQLServer HA and DR What involved in SQL Clustering How it works What’s new in 2012 HA/DR This presentation is geared towards DBAs—so feel free to stop at any time with questions
  5. 5. High Availability and DROptions in SQL 2008 SQL Server Clustering SQL Server Mirroring Peer to Peer Replication SQL Server Log Shipping*
  6. 6. Licensing (What’s changed) The Availability Group features will require the Enterprise Edition of SQL Server The licensing model for SQL Enterprise Edition has changed. Consult your friendly Microsoft sales representative for more details Mirroring is listed as being deprecated from Standard Edition. Will still be there in 2012
  7. 7. SQL Server 2012 Extended Events are used much more heavily Slipstream Install no longer required—SQL will check for updates from your Windows Update source  Can use internet Windows Update or internal source
  8. 8. Windows Core Support No GUI version of Windows Allows for fewer patches Uses PowerShell and MMCs for support
  9. 9. Windows Core
  10. 10. HA and DR Options in SQLServer 2012 Backup and Recovery Mirroring Availability Groups (2012) Log Shipping Replication SAN Replication* Virtualization*
  11. 11. What’s new in SQL Server 2012HA/DR Multi-subnet clustering is supported Flexible Failover The BIG one—Always On Availability Groups
  12. 12. Clustering
  13. 13. Clustering--2008 SQL Clustering required 1 subnet to be used across the whole cluster Cluster failover is controlled by isAlive/looksAlive processes, which check the SQL service and run @@servername
  14. 14. Clustering 2012 Fullsupport for geo-distributed clusters Flexible failover model TempDB on Non-shared Disk Resource  Makes PCI-based Solid State Drive an option  No check for this as of CTP3—instance won’t start if TempDB drive location not available
  15. 15. What is Stretch Clustering Also known as Geo-Clustering
  16. 16. Geo Cluster
  17. 17. Geo-Distributed Clustering Requires SAN replication ($$$$) Two of everything Requires really fast network connection Requires some trickery at the network/DNS level for connectivity New Term: Witness Disk  Can be physical (SAN) disk, or cluster file share
  18. 18. Multi-Subnet Cluster
  19. 19. Takeaway 2012 Thisfeature was available in 2008, just much more complicated to implement from a network perspective Won’t be used by 95% of organizations
  20. 20. Why Do Clusters Failover?• Initiated by failures in hardware or software• Checked by isAlive/LooksAlive processes (in 2008R2 and below)
  21. 21. Flexible Failover Replaces looksAlive/isAlive functionality in SQL Clusters (and is used for Availability Groups) Now runs sp_server_diagnostics  Two new parameters  HealthCheckTimeout (Default 60 sec/Minimum 15 sec)  Failover Condition Level
  22. 22. Flexible Failover Policies for ClustersLevel Condition Description No automatic failover • Indicates that no failover or restart will be triggered0 or restart automatically on any failure conditions. Failover or restart on1 • SQL Server service is down. server down • SQL Server instance is not responsive (Resource DLL cannot Failover or restart on2 receive data from sp_server_diagnostics within the server unresponsive HealthCheckTimeout settings). Failover or restart on • System stored procedure sp_server_diagnostics returns3 (Default) critical server errors ‘system error’. (Critical errors > 20) Failover or restart on • System stored procedure sp_server_diagnostics returns4 moderate server errors ‘resource error’. (Moderate errors > 17) Failover or restart on • System stored procedure sp_server_diagnostics returns5 any qualified failure ‘query_processing error’. (Deadlock) conditions
  23. 23. QuorumIt’s not just badcologne anymore
  24. 24. Understanding Quorum There are a few slides on this topic, it’s a little confusing  In a nutshell, you cluster has to be able to talk to itself to keep the cluster service up in running  This applies to both SQL Server Failover Cluster Instances and AlwaysOn Availability Groups
  25. 25. Quorum Quorum is critical—contains master copy of the cluster’s configuration Serves as a tiebreaker if network communications between cluster nodes fail If Quorum fails—cluster is shut down until it’s restored
  26. 26. Quorum Models Node and Disk Majority (Default) Node Majority No Majority (Quorum Disk Only) Node and File Share Majority (Good for Geo Clusters)
  27. 27. Quorum Failure ToleranceNumber of Nodes 2 3 4 5 6 7Node Majority 0 1 1 2 2 3Node and Disk/File Share Majority 1 2 2 3 3 4• Assuming Disk is Up Calculation is: Cluster Up = RoundUp(Total # of Nodes/2)• Assuming Disk is Down Calculation is: ClusterUp = RoundUp (Total # of Nodes/2)-1
  28. 28. DR in SQL 2008 Mirroring  Allowed automatic failover, but only one target  Mirror target is unreadable Log Shipping  Allowed multiple targets, but failover a manual process, requiring a connection string change Replication
  29. 29. AlwaysOn Availability Groups
  30. 30. AlwaysOn Requirements Windows Enterprise (Clustering is a requirement) SQL Server Enterprise Edition Windows Cluster No shared storage is required Quorum Disk Preferred
  31. 31. Flexible AG Failover Similar to how a failover clustered instance fails over Connects to instance every 30 seconds to perform health check Also, similar quorum model to Windows Failover Clustering
  32. 32. Allows for SAN Less HA/DR Thisisn’t a huge thing for SQL Server at big shops It may allow us to incorporate a level of DR into a virtual environment
  33. 33. Client Connections in ThisModel Availability Group Listener (Yes, SQL Server now has a listener)  Works just like a failover clustering instance (single instance, single IP)  Creates a VCO (AD Virtual Computer Object)
  34. 34. Contained Databases Isolate Database from Instance  Currently only fully supported with SQL Logins No numbered procedures Eases database movement Allows for ease of migration to Azure Not quite baked out as of RC0
  35. 35. Read Only Replicas Can have up to 3 SQL Client 2012 will allow for this routing specifically Can take backups from read-only copys*  Copy Only Backups (only full copy, does not affect primary log) Indexingmust be same on replicas Bad queries can affect status of replica
  36. 36. Considerations for AvailabilityGroups All SQL servers (including the secondary in the DR site) in the same Windows domain All the databases must be in FULL recovery model The unit of failover (for local HA, as well as DR) is at the AG level, i.e., group of databases – not the instance No delayed apply on the secondary Removing log shipping means the regular log backup job is removed  Need to re-establish periodic log backup (essential for truncating the log)
  37. 37. Failover Modes Automatic failover Planned manual failover (without data loss) Forced manual failover (with possible data loss)
  38. 38. Failover Synchronous- Synchronous- Asynchronous- commit mode commit mode commit mode with manual- with automatic- failover mode failover mode Automatic No No Yes failover Manual failover No Yes Yes Forced failover Yes Yes No
  39. 39. Availability Groups Demo
  40. 40. Summary Lotsof Change in the HA/DR Space Licensing also changes—talk to your MS rep SQL Server Failover Clusters still a good HA option AlwaysOn Availability Groups add a lot more flexibility to DR
  41. 41. Contact Info @jdanton jdanton1@yahoo.comhttp://spkr8.com/s/19509

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