Pssdiag and sql nexus
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The document provides an overview of SQL Server performance troubleshooting techniques, including tools like sqldiag, pssdiag, and SQL Nexus for data collection and analysis. It discusses common performance issues such as I/O bottlenecks and high CPU usage, along with important trace flags that can be utilized for optimization. Additionally, it includes references to further resources and best practices for effective performance monitoring and troubleshooting.
![I/O Troubleshooting
2015-28-08 00:00:00.00 spid1 SQL Server has encountered 192 occurrence(s) of IO requests taking longer
than 15 seconds to complete on file [E:SQLServerTestdb.mdf] in database [Testdb] (7). The OS file
handle is 0x00000000000074D4. The offset of the latest long IO is: 0x00000000022000.
The message indicates that SQL Server has been waiting on at least one I/O for 15 seconds or longer
This represents StuckStalled IO requests on SQL Server](https://image.slidesharecdn.com/pssdiagandsqlnexus-150923143016-lva1-app6892/85/Pssdiag-and-sql-nexus-9-320.jpg)
Pssdiag and sql nexus
- 1. Troubleshooting SQL Server Performance Tips & Techniques Notes from the Field Amit Khandelwal Support Escalation Engineer
- 2. Agenda Performance Troubleshooting Tools SQLDIAGPSSDIAG SQL Nexus SQL Nexus Analysis Waits analysis CPUSpinlocks Old School Tricks!!! Slow IO Troubleshooting Common Mysteries & Important Trace flags
- 4. SQLDIAG– Data collection utility Windows Event Logs (Application, System, and Security) in .CSV files System Monitor (aka Perfmon) performance counters in .BLG file/s SQL Server Profiler traces in .TRC file/s SQL Server error logs, configuration, point-in-time snapshots of several DMVs in a .OUT file System information via the Msinfo32 utility Custom scripts for collecting blocking specific data All configuration parameters are stored in SQLDiag.xml file and can be changed
- 5. PSSDIAG – Data Collection Utility Similar to SQLDIAG utility except for the user interface • CPU spikes on the SQL Server box • Performance degradation during specific hours (say between 4:00 PM and 6:00 PM daily) • Blocking on SQL Server • Overall performance bottlenecks in SQL Server using wait statistics
- 6. SQL Nexus – Data analysis tool Helpful in post-mortem analysis of performance issues Uses RML utilities (Readtrace) – It’s a pre-requisite Tool Highlights: Trace aggregation to show TOP N most expensive queries Wait stats analysis for visualizing blocking and other resource contention issues Visualize loaded data via Reports – uses SSRS client side report viewer PSSDIAG and SQL Nexus: Nexus analyses data when SQLDiag is clubbed with SQLxxxxPerfStats script SQLxxxxPerfStats scripts captures DMVs output including blocking information
- 7. PSSDIAG & SQL Nexus Hands-On
- 9. I/O Troubleshooting 2015-28-08 00:00:00.00 spid1 SQL Server has encountered 192 occurrence(s) of IO requests taking longer than 15 seconds to complete on file [E:SQLServerTestdb.mdf] in database [Testdb] (7). The OS file handle is 0x00000000000074D4. The offset of the latest long IO is: 0x00000000022000. The message indicates that SQL Server has been waiting on at least one I/O for 15 seconds or longer This represents StuckStalled IO requests on SQL Server
- 10. I/O Troubleshooting Tools and Techniques • Performance Monitor Counters (Perfmon) PhysicalDiskAv g. Disk sec/Transfer (<0.015) PhysicalDiskAv g. Disk Queue Length (<2 per spindle) PhysicalDisk% Idle Time (~100%) PhysicalDiskDisk Bytes/sec ProcessIO Data Bytes/sec(sqlserver) sys.dm_io_pending_io_requests Look out for “io_pending” column of this DMV. The io_pending column indicates 1 if the I/O is still pending within the kernel.
- 12. COMMON MYSTERIES
- 13. Common Mysteries SQL Server is using high CPU, but PSSDIAG does not show CPU getting accounted to the queries running in SQL Server!!! How does Rebuildreorg indexes affect statistics? SQL Server consumes all the memory that I give!! Why do I see huge number of child spids waiting on CXPACKET even though my MAXDOP is set to a lower value?
- 14. Important TIPS
- 15. Important Trace Flags T4199 This trace flag is a combination of a lot of optimizer related fixes released under different trace flags. T1236 Enable this trace flag when you see elevated values occur for LOCK_HASH spinlock count especially during following operations: SQL Server logins, Linked server queries, sp_reset_connection, Transactions T1117 This trace flag applies to the entire SQL Server instance, not just to one DB, and it affects all files in the same file group in a database. T1118 This trace flag forces uniform extent allocations instead of mixed page allocations. The trace flag is commonly used to assist in TEMPDB scalability by avoiding SGAM and other allocation contention points T8048 This trace flag will upgrade NODE based partitioning to CPU based partitioning. Remember this requires more memory overhead but can provide performance increases on these highly transactional OLTP systems.
- 16. Power plan setting* Max Degree of Parallelism Max Server Memory Client Side Tracing Missing Indexes DMV & Database Tuning Advisor Upgrade SQL to latest HotfixesSPs
- 17. References PSSDIAG http://diagmanager.codeplex.com/releases http://technet.microsoft.com/en-us/library/ms162833.aspx http://blogs.msdn.com/b/pamitt/archive/2011/02/25/how-to-use-the-sqldiag-the-sqlnexus-and-the-pal-tools-to-analyze-performance-issues-in-sql-server.aspx SQL Nexus http://sqlnexus.codeplex.com/ https://sqlnexus.codeplex.com/wikipage?title=GETTING_STARTED http://sqlnexus.codeplex.com/wikipage?title=Sql2005PerfStatsScript&referringTitle=Home https://sqlnexus.codeplex.com/wikipage?title=collecting%20data%20using%20batch%20files&referringTitle=GETTING_STARTED http://sqlnexus.codeplex.com/wikipage?title=readtrace&referringTitle=Sql2005PerfStatsScript Slow IO Troubleshooting http://support.microsoft.com/kb/897284 http://blogs.msdn.com/b/karthick_pk/archive/2012/06/26/io_2d00_bottlenecks.aspx http://blogs.msdn.com/b/cindygross/archive/2010/03/17/what-do-those-io-requests-taking-longer-than-15-seconds-messages-on-my-sql-box-mean.aspx
- 18. References