Monitoring Always On Avaliability Group
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The document discusses several enhancements to AlwaysOn availability groups in SQL Server 2016 including performance improvements to log transport, the ability to have availability groups span multiple domains, direct seeding to speed up secondary synchronization, and new extended events and performance counters for monitoring AlwaysOn latency. Fundamental changes include support for readable secondary replicas for load balancing, support for DTC and Group Managed Service Accounts, and native high availability in the SQL Server Standard edition.
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Monitoring Always On Avaliability Group
- 1. SQL 2016 ALWAYSON Sourabh K. Agarwal | Senior Program Manager April 11 2017 @SQLSourabh http://aka.ms/sqlserverteam | @mssqltiger
- 2. Agenda Fundamental Changes to SQL Server 2016 AlwaysOn Performance Enhancements to SQL Server 2016 AlwaysOn Domain Independent AG’s AlwaysOn Direct Seeding Database Level Failover Detection AlwaysOn Data Flow Tracking AlwaysOn Latency
- 3. Fundamental Enhancements in SQL 2016 Readable secondary's load balancing DTC support Group Managed Service Account support > 2 Auto-failover targets Basic HA in Standard edition
- 4. SQL 2016 AlwaysOn Turbocharged Streamline the Log Transport Parallel workers on separate schedulers Multiple Log Writers Parallel Redo Code Optimization Read more on our blog
- 5. Domain Independent AGs Environments have multiple domains that cannot be merged No trust relationships Installations that do not use Active Directory domains (Ex. Workgroups) All nodes in a single domain Nodes in multiple domains with full trust Nodes in multiple domains with no trust Nodes in no domain at all Read our blog docs Requires combo of Powershell scripts, T-SQL scripts, SSMS, and Windows UI blog blog
- 6. No need to initial full backups on primary Network share not required for backups Automatic restores on secondary Why Direct Seeding VDI Stream - not compressed (use TF 9567) Trade-off CPU v/s Network Bandwidth Backup/Restore process - 1 worker per reader and writer per LUN How it works Extended Events - dbseed category (debug channel) DMVs – sys.dm_hadr_automatic_seeding sys.dm_hadr_physical_seeding_stats Diagnostics Secondary AG Replica VDI Stream Primary AG Replica
- 8. CREATE AVAILABILITY GROUP [ag] WITH (DB_FAILOVER=ON) FOR DATABASE [agdb] Database level health Triggers Enabled for entire AG Log or data files read/write failures Database state != ONLINE sqlserver.availability_replica_database_fault_reporting XEvent Only when SQL Server detects a problem Independent of flexible failover policy Refresher here Ex. When we write to log
- 9. AlwaysOn Data Flow Primary Replica Secondary Replica Capture Log Block Compress Log Block Send log block to the Secondary Decompress Log Block Harden Log Block Send Ack back to Primary Commit Transactions
- 10. Detecting AlwaysOn Latency • Performance Counters • Extended Events • SSMS • PowerBI
- 11. New in SQL 2016 SP1 Extended Events recovery_unit_harden_log_timestamps log_block_pushed_to_logpool hadr_logblock_compression hadr_log_block_decompression hadr_transport_receive_log_block_message hadr_log_block_group_commit hadr_capture_filestream_wait hadr_lsn_send_complete hadr_receive_harden_lsn_message log_flush_start log_flush_complete hadr_apply_log_block hadr_capture_log_block hadr_capture_vlfheader hadr_log_block_send_complete hadr_send_harden_lsn_message ucs_connection_send_msg Perfmon counters
- 12. Is there a simpler way?
Editor's Notes
- Recommendations and fixes for WSFC: https://support.microsoft.com/en-us/kb/2920151 Pre-requisites, Recommendation and Restrictions for Always ON Availability Group: https://msdn.microsoft.com/en-us/library/ff878487.aspx Readable secondaries load balancing: https://blogs.msdn.microsoft.com/alwaysonpro/2016/05/02/sql-server-2016-alwayson-availability-group-enhancements-load-balance-read-only-routing/ Log transport performance - https://blogs.msdn.microsoft.com/bobsql/2016/09/26/sql-server-2016-it-just-runs-faster-always-on-availability-groups-turbocharged/ Multiple automatic failover targets - https://blogs.msdn.microsoft.com/alwaysonpro/2016/05/02/sql-server-2016-alwayson-availability-group-enhancements-multiple-automatic-failover-targets/ Support for encrypted databases - https://blogs.msdn.microsoft.com/alwaysonpro/2016/06/23/sql-server-2016-alwayson-availability-group-enhancements-support-for-encrypted-databases/ Basic Availability Groups - https://msdn.microsoft.com/en-us/library/mt614935.aspx DTC support: https://msdn.microsoft.com/en-us/library/ms366279.aspx#dtcsupport
- During this Data flow, latency can happen on any of the following location Disk (Mostly on the Secondary) Network (Both Primary/Secondary) CPU
- Add in how to get there from SSMS Why not by default? How expensive is this?