Troubleshooting Always On Availability Groups Performance

Transcription

1 Andreas Wolter Troubleshooting Always On Availability Groups Performance Andreas Wolter (SQLMCM) 1

2 About: Andreas Wolter Consultant, Trainer & Speaker Microsoft Certified Master SQL Server Solutions Master Data Platform (SQL Server 2012) Datawarehouse & OLTP-System Architecture Performance Tuning Security a.wolter AT SarpedonQualityLab.com Blog: Facebook: LinkedIn: SQL Server 2012 SQL Server SSAS, SSRS, SSIS 7 Agenda Under the covers fundamentals of the engine Automatic Seeding Error-Analysis Performance-Analysis Synchronisation-Traffic Performance-Analysis Performance-Overhead on the Workload Lag on Secondary Failover Super-fast under all circumstances? 8 Andreas Wolter (SQLMCM) 2

3 9 Monitoring Tools at hand Availability Groups Dashboard Windows Performance Monitor (Perfmon.exe) DMVs sys.availability_* sys.dm_hadr_* Extended Events AlwaysOn_health-session Errorlog ClusterLog Mainly for troubleshooting problems with Failover 10 Andreas Wolter (SQLMCM) 3

4 The Availability Groups Dashboard Use primarily on Primary Group state only available on Primary Information on all nodes health states only on primary But also check Secondaries in case or error that have remote causes Shows the assigned Cluster Quorum Votes, including File Share Witness Direct access to AlwaysOn_health extended events session Not merged across nodes! Need to open on each secondary toget the full picture Demo time 12 Andreas Wolter (SQLMCM) 4

5 13 Perfmon Patterns 14 Andreas Wolter (SQLMCM) 5

6 Perfmon Patterns 15 Perfmon Patterns 16 Andreas Wolter (SQLMCM) 6

7 Perfmon Patterns 17 Perfmon Patterns 18 Andreas Wolter (SQLMCM) 7

8 DMV 23 sys.dm_hadr_database_replica_states The values of the end_of_log_lsn, last_hardened_lsn, last_received_lsn, last_sent_lsn, recovery_lsn, and truncation_lsn columns are not actual log sequence numbers (LSNs). Rather each of these values reflects a log-block ID padded with zeroes. end_of_log_lsn, last_hardened_lsn, and recovery_lsn are flush LSNs. last_hardened_lsn indicates the start of the next block past the blocks that are already on disk. So any LSN < the value of last_hardened_lsn is on disk. LSN that are >= to this value are not flushed. only last_redone_lsn is a real LSN You can use the following query to see how far the redo thread has fallen behind, by measuring the difference between last_redone_lsn and last_received_lsn. Select recovery_lsn, last_hardened_lsn, last_received_lsn, last_redone_lsn, last_redone_time from sys.dm_hadr_database_replica_states Waits 27 Andreas Wolter (SQLMCM) 8

9 Disk Performance & Waits on Primary 28 Xevents for detailed flow 37 Andreas Wolter (SQLMCM) 9

10 Learnings Latency and Throughput are vital Network IO Wait-Stats only get you so far If I may say so: a professional tool is a must, if you take HA seriously 38 Thank you Andreas Wolter Contact: LinkedIn: Twitter: a.wolter AT Sarpedon.de 39 Andreas Wolter (SQLMCM) 10

11 We are one of only 2 companies worldwide who have reached the highest technical certifications from Microsoft for SQL Server 2008 as well as SQL Server 2012! Sarpedon Quality Lab: Your Specialist for Database-Systems based on SQL Server Technologies We love to support you and use our know-how to your advantage. our Services cover: SQL Server Health checks Performance Analysis & Tuning Disaster-Recovery & SLA-Compliance-Checks Security-Checks Data Rescue in case of corruption Architecture-Planning, Consulting and Implementation Training: Ask us: info AT Sarpedon.de Partner of Ask us for the best Performance Monitoring & Troubleshooting Solution for SQL Server on the Market. SentryOne SQLSentry AlwaysOn Monitoring Exclusive 45-Day Test-License: 41 Andreas Wolter (SQLMCM) 11

12 Performance Dashboard Professional Monitoring of SQL Server Azure SQL DB, Managed Instances and Azure DW Event-Calenar Availability Group Dashboard File-Activity Monitor Lowest Monitoring-Overhead in the industry! Andreas Wolter (SQLMCM) 12