1.
TOP 10 ADMIN
MISTAKES ON SQL
SERVER
Kevin Kline
• Director of Engineering Services, SQL Sentry
• SQL Server MVP since 2003
• Twitter, FB, LI: KEKline
• Blog: http://KevinEKline.com, http://ForITPros.com

2.
AGENDA
• About SQL Sentry
• The Top 10 Countdown: DBA Mistakes on
Microsoft SQL Server
o Mistakes come in surprising forms
o Often people & process, instead of technology
• Summary, Resources, and Q&A

3.
FOR FRIENDS OF SQL SENTRY
• Free Plan Explorer download:
http://www.sqlsentry.net/plan-explorer/
• Free query tuning consultations:
http://answers.sqlperformance.com.
• Free new ebook (regularly $10) to attendees.
Send request to sales@sqlsentry.net.
• SQL Server educational videos, scripts, and
slides: http://SQLSentry.TV
• Tuning blog: http://www.sqlperformance.com/
• Monthly eNews tips and tricks:
http://www.sqlsentry.net/newsletter-archive.asp

4.
TOOLS FROM SQL SENTRY

5.
OTHER TOP SQL SERVER MISTAKES
Excludes SQL Server mistakes
that are primarily development or
design in nature:
o Inadequate normalization and
database design
o Unknown scalability
requirements
o No baselines or benchmarks
o Indexing issues
o Query tuning ignorance

6.
10. DISKS – THINKING SPACE BUT NOT IO
• Frequently think about disk subsystems only in terms of
disk space, not IO load.
• Without this knowledge, the following problems occur:
o Inadequate fault tolerance
o Insufficient IO:
• OLTP requires high transactions/sec
• OLAP requires high MB transfers/sec
o Poor choice of RAID type, controllers, channels
o Not enough disk spindles
• SSD is a game changer for IO!

7.
9. BUSINESS IGNORANCE
• As the IT professional, you should know how SQL Server
works at an “internals” level.
o What is checkpoint? Lazywriter?
o How is TempDB used? What’s in the plan cache?
• The DBA is the guardian of the corporate data assets.
• As the liaison between business and IT, you should know how
For more tech info:
- SQLPASS.org
- SQL University
- SQL Crunch
- SQLBlog.com
and in what ways your servers are used.
o Who cares if this app is down? How much does the downtime cost the company?
o What are the business cycles?
o When are the best downtimes?
o Baseline? Benchmarks? What is normal?

8.
BONUS BLUNDER: NOT ASKING…
• …for help:
• Forums vs Support: know the value
• #sqlhelp and Twitter
• …for mentoring:
• Senior bloggers love to mentor!

9.
8. NO TROUBLESHOOTING
METHODOLOGY
• When the chips are down, the DBA needs a
strong, step-by-step methodology for root-cause
analysis. Without one, you get:
o Missed errors and problems
o Errors resulting data loss and catastrophic failure
o Poor response times and breached SLAs
o Lost credibility
• Don’t have a methodology? Check out End-to-
End Troubleshooting on http://SQLSentry.TV
• SQL Server Troubleshooting Guide by J.
Kehayias on http://www.simple-talk.com

10.
BONUS BLUNDER: REACTIVE NOT
PROACTIVE
• DEMO

11.
DEMO: ERROR NOTIFICATIONS

12.
7. GOING WITH THE DEFAULTS
• SQL Server installation defaults are intended to get the
server up and running, but not running optimally:
o Auto-grow and Auto-shrink on databasese
o Auto sizing of auto-growing databases
o Default filegroups
o Minor issues can become major issues:
• MAXDOP
• FILLFACTOR
o Many server- and database-level configuration settings

13.
6. SECURITY AS AN AFTERTHOUGHT
• SQL Injection is the #1 hack on the internet today.
o Remarkably, we knew as much about preventing SQL Injection ten years
ago as we do today.
• Plan ahead of time to minimize issues:
o Ensure the least privileges principle for applications running on your servers
o How much surface area do your servers expose?
o Who has access to your servers?
o How do you find out the who, what, and when of a breach?
• See my session Understanding & Preventing
SQL Injection for more info

14.
5. INADEQUATE AUTOMATION
• Automation is the means by which DBAs work “smarter”
instead of “harder”. Ironically, it takes a lot of work at the
outset to automate.
• Without automation, DBAs must deal with:
o Manual processes prone to error, omission, and forgetfulness
o Inability to scale environment to multiple servers
o Time constraints from fire-fighter and script-pusher modes
• Examples of working smarter instead of harder:
o Automated error notification
o Scheduled jobs
o Lots of scripts, not too much GUI
Automation made easy
with PowerShell and/or
WMI:
- PowerGUI
- Scriptomatic

15.
4. WRONG FEATURE OR TECHNIQUE
FOR THE JOB
• DBA’s are the “performance engineer” for their corporation’s
IT applications.
• It’s imperative that the most appropriate feature be applied to
each business requirement. Otherwise:
o Brittle applications
o Applications complexity
o Excess resource consumption
o “Ooooh! Shiny!”
o Design reflects the current “fad”
• Axiom: There are no IT projects. There are business projects
solved using IT.

16.
3. APATHY ABOUT CHANGE
MANAGEMENT
• Change management is important! Without it, DBAs face:
o Changes that leave things worse than they started
o Piecemeal rollbacks that cripple applications
o Inconsistent support across applications and servers
• Change control versus Change management?
• Proper change management means:
o Key stakeholders have a say in Go-NoGo (CM board)
o Performed at pre-planned times and within a defined time limit
o Change is tested and verified to have no effect or positive effect on production
environment
o Changes are isolated, atomic, and reversible

17.
2. INADEQUATE PREVENTATIVE
MAINTENANCE
• Proper preventative maintenance (PM) helps you:
o Catch issue before they become problems
o Ensure optimal performance
o Perform resource intensive operations with few, if any, users on the system
• PM on SQL Server should include:
o Database consistency checks (DBCC) and CHECKIDENT
o Backups with verification & Restore checks
o Defragmentation, Fill factor, Pad Index
o Index Statistics
• Don’t rely on the Database Maintenance Wizard!

18.
BONUS BLUNDER:
REINVENTING THE WHEEL
• Most PM has already been written and vetted by
others.
• Check out:
o www.sqlfool.com
o www.olahallengren.com

19.
1. BACKUPS <> RECOVERY
DBAs often don’t test backups or recoveries as they
should. Causes lots of problems:
o Can you meet your SLA? RTO? RPO?
o Not certain that backups are good: verified and available?
o Where’s all the data, files, It’s
DLLs, etc for recovery?
o Got all of the databases that are needed?
o Haven’t tested a full, ground-up restore:
All About
The Data, All
The Time, Every
• What if you have to reinstall everything?
o One of the great things about VM recovery!
• The importance of recovery: the Lost Job scenario
o Can you actually restore older, archived data?
Time

20.
SUMMARY

21.
RESOURCES
• http://www.sqlcat.com - Excellent source of SQL
Server best practices, white papers, etc.
• Paul Randal and all the blogs at SQLSkills –
http://www.sqlskills.com/blogs/paul/ et al
• http://SQLPerformance.com
• http://www.sqlpass.org

22.
Q & A
• Send questions to me at: kkline@sqlsentry.net
• Twitter, Facebook, LinkedIn at KEKline
• Slides at http://SQLSentry.TV
• Kevin’s IT leadership and soft-skills content at
http://ForITPros.com
THANK YOU!