Performance Tuning for Pirates!

PERFORMANCE TUNING FOR
PIRATES!

John Sterrett (@JohnSterrett)
HTTP://JOHNSTERRETT.COM/GO/PERFORMANCE

ABOUT John…

I am a Remote DBA Expert
• Responsible 100+ Instances of SQL Server
• Senior DBA on Integration Team
Mid-Atlantic Region Mentor
Founder of WVPASS (SQL UG)
Host of SQL Saturday #36 and #80
I reside in Wheeling, WV (Pittsburgh, PA)

2

Pirates and Yankees

Photos: http://www.flickr.com/photos/jaubele1/4299542394/ and http://www.flickr.com/photos/wenzday01/2537854102

3

Objectives

• Eliminate the Obvious
• Know the process
• Know the common bottlenecks
• Know your Tools
– Wait Stats
– Performance Monitor & PAL (WMI Counters)
– DMV’s and scripts
– SQL Server Side Trace (SQL Profiler)
– Clear Trace
– SQL Diag
– SQL Nexus
– RML Utilities
• ReadTrace
• Ostress
• Know where to go for help...

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Eliminate the Obvious

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Eliminate the OBVIOUS

http://theiphonefever.blogspot.com/2010/10/movies-you-should-watch-office-space.html

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Know the process!

Generate
workload

Make Capture
Changes workload

Analyze
captured
workload

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12 Steps to workload Tuning

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1. Backup Production Database

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2. Capture Production Workload

10


3. Analyze Workload and Script Changes (Don’t
Implement)

*** Done with Production ***

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Implement)
4. Restore Backup on Test Server

12


Implement)
5. Prepare to capture Workload on Test Server

13


Implement)
6. Replay Production Workload on Test Server

14


Implement)
7. Analyze to Establish Baseline

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Implement)

16


Implement)
9. Make Changes to Improve Performance on Test Server

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3. Analyze Workload and Script Changes (Don’t Implement)
10. Prepare to Capture Production Workload on Test Server

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11. Replay Workload on Test Server

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11. Replay Workload on Test Server
12. Analyze and Compare Workload with Baseline
*** Repeat Steps 8 to 12 as needed ***
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Where can things Go wrong?

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Meet the Bottlenecks

MEMORY DISK (SPINDLES) CPU

NETWORK LOCKING, BLOCKING & DEADLOCKS
Photos: http://www.flickr.com/photos/kaiban/5159888367/lightbox/ and http://www.flickr.com/photos/moodog/504456253 and
http://www.flickr.com/photos/marksze/4231115464 and http://www.flickr.com/photos/vvvracer/5264339383 and
http://www.flickr.com/photos/iphil_photos/4962369046

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3 Options To Resolve bottlenecks

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1. Reduce Workload

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1. Reduce Workload
2. Tune Workload to reduce bottleneck resource

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1. Reduce Workload
2. Tune Workload to reduce bottleneck resource
3. Add additional Hardware

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Viewing Wait Stats

• Sys.dm_os_wait_stats
• Wait stats can be cleared manually or during restart.
– DBCC SQLPERF(‘sys.dm_os_wait_stats’, CLEAR)
• Focus on waits dedicated to bottlenecks

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Common WAIT STATS

• ASYNC_NETWORK_IO
• LCK_M_*
• IO_COMPLETION
• PAGELATCH_* or PAGEIOLATCH_*
• WRITELOG
• CX_PACKET
• SOS_SCHEDULER_YIELD

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DEMO!!!!

• Review Wait Statistics

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Memory Performance counters

You Want Description
Object Counter
> 256 MB Unused physical memory
Memory Available Mbytes
< 10 Reads from hard disk per second to memory
Memory Pages Input/sec
> 300 On average, how many seconds SQL Server expects page to say in cache
(memory)
SQL Server: Buffer Manager Page Life Expectancy
Shows amount of memory SQL Server is currently using.
SQL Server: Memory Manager Total Server Memory (KB)
Amount of memory that SQL Server wants to use based on configured max
Server Memory setting
SQL Server: Memory Manager Target Server Memory (KB)
0 Total number of processess pers second waiting for workspace memory grants
SQL Server: Memory Manager Memory Grants Pending
> 640 Total number of pages avaiable across all free lists. A value under 640
SQL Server: Buffer Manager Free Pages
< 20 Number of times per second that the lazywritter process moves dirty page from
buffer to disk.
SQL Server: Buffer Manager LazyWrites/Sec

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Disk Performance Counters

• The sys.dm_io_virtual_file_stats DMV can be used to get disk latency for
individual sql server files.

Object Counter You Want Description

Avg. Disk sec/Read is the average time, in seconds, of a read of data from the disk.This
analysis determines if any of the physical disks are responding slowly.

Physical Disk Avg Disk Sec/Read < 25ms
Avg. Disk sec/Write is the average time, in seconds, of a write of data to the disk.

Physical Disk Avg Disk Sec/Write < 25ms
Disk Reads/sec is the rate of read operations on the disk.
Physical Disk Disk Reads/sec
Disk Writes/sec is the rate of write operations on the disk.
Physical Disk Disk Writes/sec

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CPU Performance Counters


< 80% Percentage of processor time spent on SQL Server process threads.
Process (sqlservr) %Processor Time
< 80% Percentage of elapsed time the processor spends executing non-idle threads.
Processor %Processor Time

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General Workload performance
counters

Number of SQL batch requests received by server. This counter
measures the number of batch requests that SQL Server receives per
Batch Requests/Sec second, and generally follows in step to how busy your server's CPUs
SQL Server: SQL Statistics (SQL2005/08) are.
< 10% of the number of Number of SQL compilations.
SQL Server: SQL Statistics SQL Compilations/sec batch request/sec
< 10% of the number of Number of SQL re-compiles. This needs to be 0 as much as possible. A
compilations/sec recompile can cause deadlocks and compile locks that are not
SQL Server: SQL Statistics SQL Re-Compilations/sec compatible with any locking type.

SQL Server: SQL Statistics User Connections
1 Full scan for every 1000 This counter monitors the number of full scans on base tables or
index searches indexes. High values indicate that we may be having performance
SQL Server: Access Methods Full Scans/sec issues due to table / index page scans.
This counter measures the number of index searches per second. Index
searches are used to start range scans, single index record fetches, and
to reposition within an index. Index searches are preferable to index
SQL Server: Access Methods Index Searches/sec and table scans.
Number of page splits per second that occur as a result of overflowing
index pages. Reduce non-sequential inserts or use fill factor and
SQL Server: Access Methods Page Splits/sec pad_index to leave more empty space per page.

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Locking Performance Counters


Number of lock requests per second
SQL Server: Locks Number of Deadlocks/sec <1 that resulted in deadlock.
Number of times SQL escalated
locks to table level. This can indicate
SQL Server: Locks Table Lock Escalations/sec poorly coded transactions.
The average wait time for each lock
SQL Server: Locks Avg Wait Time (ms) < 500 request that had to wait.
Number of currently blocked
SQL Server: General Statistics Processes blocked processes.

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DEMO!!!

• Review Perfmon
• Review PAL Tool
– Collection Process
– Generating Reports
– Reviewing Reports
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Execution DMV’s

• Sys.dm_exec_session
– Returns one row per authenticated session, including user and
system processes.
• Sys.dm_exec_requests
– Returns one row for each request executing within SQL Server,
doesn’t include code executed outside of SQL (distributed queries,
extended stored procedures etc…)
• Sys.dm_exec_query_stats
– Returns one row per query statement with cached plan, detailing
aggregated performance stats for cached plans.
• Sys.dm_exec_connections
– Returns server information about a connection to SQL Server
including client network address, TCP Port etc..

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Query details DMV’S

• Sys.dm_exec_sql_text
– Returns the text of the SQL Server batch that is identified by
specific sql handle.
• Sys.dm_exec_text_query_plan
– Returns the showplan output in text format.
• Sys.dm_query_plan
– Returns a given query’s showplan output in xml.

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INDEX DMV’s

• Sys.dm_db_index_usage_stats
– Returns a count of index operations including seeks, scans, lookup
and updates
• Sys.dm_db_index_physical_stats
– Returns size and fragmentation information for data pages and
indexes.
• DMV’s to find recommended indexes
– Sys.dm_db_missing_index_columns
– Sys.dm_db_missing_index_details
– Sys.dm_db_missing_index_groups
– Sys.dm_db_missing_index_group_stats

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SQLOS DMV’s

• Sys.dm_os_sys_memory
– Returns complete picture of memory at the os level including total and
available memory.
• Sys.dm_os_tasks
– Returns a row for each OS task thais is active in the instance of SQL
Server.
• Sys.dm_os_threads
– Returns a row for each SQLOS thread running under the SQL Server
process.
• Sys.dm_os_performance_counters
– Returns a row for each SQL Server perfmon counter.
• Sys.dm_os_waiting_tasks
– Returns information about the wait queue of SQLOS. This would be
tasks waiting on resources like blocking and latch contention etc..

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DMV Queries (DEMO)

http://www.flickr.com/photos/democonference/4458079104
• What is Running?
• Probing the Proc Cache

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SQL Profiler (DEMO!)

• Generate Server Side traces
– Tuning Columns and Events
– Remove the noise
• Read Trace with Clear Trace
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SQL Diag (DEMO)

• Review SQL Diag
• Review PerStats Scripts
• Collect perfmon, sql trace, blocking and more…
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SQL NEXUS (DEMO)

• Import SQLDiag
• Analysis collected data

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RML Utilities (DEMO)


• Ostress (Replay)
• ReadTrace (Compare Workload to Baseline)
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Help I need Some One!!!!

• Performance Virtual Chapter
– http://performance.sqlpass.org/
• Twitter (#sqlhelp)
• Message boards
– www.sqlservercentral.com
– www.msdn.com
• Blogs
• Consultants

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Where to go next?

• HTTP://JOHNSTERRETT.COM/GO/PERFORMANCE
– Videos
– Reference Links
– Slides

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Performance Tuning for Pirates!

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