This document discusses best practices for virtual machines (VMs), storage area networks (SANs), and SQL Server. It provides three "nevers" for VMs: never overallocate virtual CPUs, never use automatic settings, and never assume VMs are alone. It also gives three "always" for SANs: always know your neighbors on the SAN, always test storage performance first with SQLIO before SQL Server, and always be checking performance metrics. Key metrics discussed include processor queue length, SQL Server memory page life expectancy, and physical disk read/write average time. The document emphasizes testing storage, understanding competition from other workloads, and monitoring for subtle performance changes.

1. VMs, SAN, SQL:The Big Threes Brent OzarQuest Software Photo Licensed with Creative Commons From http://www.flickr.com/photos/ektogamat/2687444500/

2. I’m Your Host: Brent Ozar Microsoft Certified Master SQL Server MVP Quest Software Past Lives: DBA, SAN, VMware admin www.BrentOzar.com Twitter: @BrentO

3. Today’s Big Threes 3 “Nevers” for VMs 3 “Always” for SAN 3 Metrics for Both Photo Licensed with Creative Commons From http://www.flickr.com/photos/ektogamat/2687444500/

4. Some Definitions

5. Our Host 2 Sockets4 Cores Each 64GB RAM 1 Terabyte SAN Photo Licensed with Creative Commons From http://www.flickr.com/photos/brento/1748661584/

6. The Brochure Says…

7. CPU Scheduling

8. CPU Scheduling

9. CPU Scheduling

10. Not So Fast!

11. Never OverallocatevCPUs Less is More Every Tick Matters Minimize CPU Work Don’t Be Strict Photo Licensed with Creative Commons From http://www.flickr.com/photos/rsimpson/3832084595/

12. So What About Memory? Host: 64GB Guest: 16GB Other Guests: 32GB Photo Licensed with Creative Commons From http://www.flickr.com/photos/erikthenorsk/3642116265/

13. So What About Memory? Host: 64GB Guest: 16GB Other Guests: 80GB Photo Licensed with Creative Commons From http://www.flickr.com/photos/erikthenorsk/3642116265/

14. How Hypervisors Cope Host page file Dedupe memory(page sharing) Keep guest OSmemory freed up Learn more inmy bookmarks:http://delicious.com/brento/balloon Photo Licensed with Creative Commons From http://www.flickr.com/photos/heartlover1717/208534358/

15. Never Use Automatics Set SQL Server’s min/max memory Set VMware’s reservation size Use locked pagescarefully Photo Licensed with Creative Commons From http://www.flickr.com/photos/nataliejohnson/2419154951/

16. Physical Storage Setup

17. In Virtualization…

18. Behind the Curtain

19. Behind the Curtain

20. Think You’re Alone?

21. Never Assume VMs are Alone Guests move Guests get created Competition: virus scans, scheduled tasks, backups Photo Licensed with Creative Commons From http://www.flickr.com/photos/32172473@N00/4036700968/

22. Always Know Your Neighbors Same disks Same cache Same controller Same SAN Ask: Usage pattern? Scheduled jobs? Antivirus? Photo Licensed with Creative Commons From http://www.flickr.com/photos/searchnetmedia/4327761697/

23. Design Storage as a Whole Backup schedules Backup methods Backup targets Use differentials Stagger job times Reconfigure antivirus

25. Controllers (& Cache)

26. Switch networks

27. Host Bus Adapters

28. HBA Drivers

30. What Does Active/Active Mean? One path per LUN Sending vs receiving Network design Post-failover stickiness

31. Got High Speed?

32. So You Tested This Too, Right? Photo Licensed with Creative Commons From http://www.flickr.com/photos/tophost/2247031208/

33. Always Test First with SQLIO Doesn’t use SQL Server Doesn’t mimic SQL Server Doesn’t return SQL metrics Therefore: SAN guys love it!

34. The Easy Way

35. SQLIO Results E:rogram Files (x86)QLIO>sqlio -kW -t2 -s120 -dM -o1 -frandom -b64 -BH -LS Testfile.dat sqlio v1.5.SG using system counter for latency timings, -1361967296 counts per second 2 threads writing for 120 secs to file M:Testfile.dat using 64KB random IOs enabling multiple I/Os per thread with 1 outstanding buffering set to use hardware disk cache (but not file cache) using current size: 24576 MB for file: M:Testfile.dat initialization done CUMULATIVE DATA: throughput metrics: IOs/sec: 1539.50 MBs/sec: 96.21 latency metrics: Min_Latency(ms): 0 Avg_Latency(ms): 0 Max_Latency(ms): 572 histogram: ms: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24+ %: 66 32 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

36. Good Numbers, Bad News iSCSI 1GB = 125 MB/sec 10GB = 1250 MB/sec Fibre Channel: 2GB = 250 MB/sec 4GB = 500 MB/sec

37. Which Causes An Outage? New neighbors RAID restripe Drive failure Cable change Firmware change Switch upgrade Controller reboot Photo Licensed with Creative Commons From http://www.flickr.com/photos/celebdu/10200825/

38. Where Will You See Changes? Windows event log SQL Server logs Profiler traces Net Send popups Your dreams at night

39. Always Be Checking Photo Licensed with Creative Commons From http://www.flickr.com/photos/buro9/298998173/

40. My 3 Favorite Metrics Physical Disk: Avg Sec/Read and Write System: Processor Queue Length SQL Server Memory: Page Life Expectancy

41. It’s Not All Bad News! Easier scaling Less firmware outages No leased hardware cycles Easier disaster recovery Easier dinosaur handling

42. Wrapping It Up Virtualization Nevers: OverallocatevCPUs Use automatics Assume your VM is alone SAN Always’s: Know your neighbors Test first with SQLIO Be checking

43. http://www.BrentOzar.com/go/virtual

44. Our Book Internals: Memory Locking Storage Troubleshooting: Perfmon/Profiler RML Utilities SQLNexus

45. Our Authors Christian BoltonMVP, MCM, MCAFormer Microsoft PFE Justin LangfordFormer MS PFE Brent OzarMCM, MVP James Rowland-JonesMVP, EMC Consulting Steven WortMicrosoft Developer

46. Paperbacks & PDF Versions:SQLServerTroubleshooting.com