Top 10 DBA Mistakes on SQL Server

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Other Top SQL Server Mistakes Excludes SQL Server mistakes that are primarily development or design in nature: Inadequate normalization and database design Unknown scalability requirements No baselines or benchmarks Indexing issues Query tuning ignorance

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

What is checkpoint? Lazywriter? 9. Business Ignorance As the IT professional, you should know how SQL Server works at an “internals” level. What is checkpoint? Lazywriter? 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 and in what ways your servers are used. Who cares if this app is down? How much does the downtime cost the company? What are the business cycles? When are the best downtimes? Baseline? Benchmarks? What is normal? For more tech info: SQLPASS.org SQLPerformance.com

Bonus Blunder: Not Asking …for help: Forums vs Support: know the value #sqlhelp and Twitter

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: Missed errors and problems Errors resulting data loss and catastrophic failure Poor response times and breached SLAs Lost credibility Don’t have a methodology? Check out End-to-End Troubleshooting on: http://sqlsentry.tv/end-to-end-troubleshooting-on-microsoft-sql-server/ SQL Server Troubleshooting Guide by J. Kehayias on: https://www.simple-talk.com/books/sql-books/troubleshooting-sql-server-a-guide-for-the-accidental-dba/ Mention the book “Checklist Manifesto”, site examples like nurses routines on checklist reducing 47% errors when medicating patients. Where to start How to use the native troubleshooting tools: Error logs & automated error notification SQL Profiler and server-side traces PerfMon Query plans

Bonus Blunder: Reactive not proactive In the SQL Server Management Studio, select the Instance >> SQL Server Agent >> Alerts >> Rt-click New Alert >> Type in an alert name >> Select the Severity Radio Button >> Choose the appropriate severity level from the drop-down list. Note that you can also create performance alerts, such as “alert me when buffer cache hit ratio drops below 80%”. However, you have to know what PerfMon counter and what value of that counter you want SQL Server Agent to watch for. Once you’ve created the alert, you then want to set the response. Typically, your response will be to email a first responder, such as the DBA, though you could also execute a T-SQL job.

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

6. Security as an afterthought SQL Injection is the #1 hack on the internet today. Remarkably, we knew as much about preventing SQL Injection ten years ago as we do today. Plan ahead of time to minimize issues: Ensure the least privileges principle for applications running on your servers How much surface area do your servers expose? Who has access to your servers? How do you find out the who, what, and when of a breach? See my session Understanding & Preventing SQL Injection at https://sqlbits.com/Sessions/Event8/Understanding_and_Preventing_SQL_Injection_Attacks

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: Manual processes prone to error, omission, and forgetfulness Inability to scale environment to multiple servers Time constraints from fire-fighter and script-pusher modes Examples of working smarter instead of harder: Automated error notification Scheduled jobs Lots of scripts, not too much GUI Automation made easy with PowerShell and/or WMI: PowerGUI Scriptomatic

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: Brittle applications Applications complexity Excess resource consumption “Ooooh! Shiny!” Design reflects the current “fad” Axiom: There are no IT projects. There are business projects solved using IT.

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

2. Inadequate Preventative Maintenance Proper preventative maintenance (PM) helps you: Catch issue before they become problems Ensure optimal performance Perform resource intensive operations with few, if any, users on the system PM on SQL Server should include: Database consistency checks (DBCC) and CHECKIDENT Backups with verification followed by restore checks Defragmentation, Fill factor, Pad Index Index and Statistic maintenance Full app recovery (logins in Master, jobs in MSDB, repl, etc)

Bonus Blunder: Reinventing the wheel Most preventative maintenance tasks have already been written and vetted by others. Check out: Ola.hallengren.com www.midnightsql.com/minion

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

2. Most DBA blunders are due to process and business issues: Summary Let’s connect! Facebook, LinkedIn, Twitter at KEKLINE. Email at KKline@SentryOne.com More slides at http://slideshare.net/kkline84 More videos at http://SQLSentry.TV 1. Only a few big DBA blunders are due to tech skills: Disks as space, not IO No troubleshooting methodology Going with the defaults 2. Most DBA blunders are due to process and business issues: Security as an afterthought Wrong features Change management Preventative maint & automation Backups <> Recovery