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Sql saturday powerpoint dc_san

  1. 1. SAN Basics for DBAs Joey D’Antoni November 5, 2011
  2. 2. About Me  Senior SQL Server DBA at Comcast  Blog:  Twitter @jdanton  Email 11/7/2011 2 | Footer Goes Here |
  3. 3. Storage  Understanding Storage Types  A little bit about SSDs  RAID Levels  Components of a SAN  SAN Benefits  SANs and DR  Summary
  4. 4. Storage
  5. 5. Different Kind of Storage
  6. 6. Hard Drive Components
  7. 7. Caching  Almost all hard drives (SAN, standalone) have some form of caching (RAM in front of storage)  For SQL Servers—make sure you have a battery backed cache—if you don’t and power fails—you will lose data!
  8. 8. Why is storage the bottleneck?
  9. 9. Disk Drives  Hard Drives can only spin at 15,000 RPM.  Hard Drive Performance has improved approximately 50x  Have grown in capacity  During the performance improvement CPU speed increase 5521x
  10. 10. Latency  ―Disk latency is around 13ms, but it depends on the quality and rotational speed of the hard drive. RAM latency is around 83 nanoseconds. How big is the difference? If RAM was an F-18 Hornet with a max speed of 1,190 mph (more than 1.5x the speed of sound), disk access speed is a banana slug with a top speed of 0.007 mph.‖ --credit Christian Paredes Blue Box Group
  11. 11. CPU and Disks  As CPUs have gotten faster they have the ability to drive more IOPs.  Modern CPUs are so powerful they can saturate a 10 GB connection with I/O requests—your disks can’t possibly keep up
  12. 12. SSDs (Solid State Drives)
  13. 13. SSDs are Fast  Much faster on random reads and writes  At least 5x better performance, often much more  Up to 350x faster on seeks  Not nearly as much of difference on sequential reads and writes
  14. 14. SSDs are Expensive  List Prices From Fusion-IO 160GB SLC ioDrive - $8495 320GB SLC ioDrive - $15495 320GB MLC ioDrive - $7495 640GB MLC ioDrive - $11495 320GB SLC ioDrive Duo – 16,990 640GB SLC ioDrive Duo - $30,990 640GB MLC ioDrive Duo - $14,990 1.28TB MLC ioDrive Duo - $22,990  These are really great for TempDB
  15. 15. RAID  RAID—Redundant Array of Independent Disks  Hard Drives Will Fail, RAID is what gives you protection from that
  16. 16. RAID 0
  17. 17. RAID 0, Don’t Do This  From a major virtualization vendor benchmark
  18. 18. RAID 0  No data protection at all  Best performance  If you lose one disk, you lose it all  As you add disks risk increases
  19. 19. RAID 1--Mirroring  Mirroring  No increase in write performance  Read performance is increased  50% Capacity Loss
  20. 20. RAID 5—Striping (What you SAN Admin Wants)  Maximum Capacity  Big Write Penalty— gets worse as more disks are added  Not good for highly transaction databases  BAARF
  21. 21. RAID 1+0 (10) Mirrored Striping  Best performance  Requires 4 or more drives  Only 50% of actual capacity is used
  22. 22. Summary of RAID Levels  Ask for RAID 10 for Everything (you won’t get it)  Make sure your TempDB and Logs are on RAID 10  NEVER USE RAID 0!!!
  23. 23. Storage Area Network
  24. 24. What is a SAN?  Basically a specialized computer for storage  Computer, Switches and Hard Drives  Not a performance device  Can be used for redundancy and DR purposes  Will serve many servers—so critical piece of your infrastructure
  25. 25. SAN Components  HBA (Fibre) Card—Connects your server to SAN via Fiber Optic cable  iSCSI Card—Ethernet Card connecting server to SAN  Switch—Either fibre or ethernet switch connecting server to SAN  SAN head unit—Controls processing, RAID levels  Disk Array—The physical array behind your SAN (a bunch of hard drives)
  26. 26. iSCSI vs Fibre Channel  iSCSI is cheaper, and in smaller shops your network admin can manage the switches  Over 10G Ethernet iSCSI is faster, but that is still uncommon  Fiber is more susceptible to breakage, but currently more common  Fibre is faster, generally  Note—all SAN components must be the same speed, or network traffic reverts to slowest in chain
  27. 27. Multi-Pathing  How your SAN admin sleeps at night!  Make sure your databases servers are multi-pathed
  28. 28. SAN Benefits  Expand Capacity easily and on the fly  High availability  Disaster Recovery
  29. 29. SANs and DR  WARNING!—Don’t try this unless you have a real budget and a good SAN admin  Most SANs vendors have as an option SAN replication  Allows for multi-site failover  Multi-site clustering fully supported in SQL Server 2012  Expensive—requires fiber connection between sites and expensive software
  30. 30. SAN Terms  LUN—Logical Unit Number, but in practical terms, what your SAN admin will call a disk that he presents to your server  Fibre Channel—Fiber Optic connection to SAN  HBA Card—Card that plugs into your server to connect it to the SAN  IOPs—I/O Operations Per Second—the way your SAN admin measures performance
  31. 31. SANs and SQL Server—What to ask for  TempDB absolutely needs its own disk (and you should have multiple TempDB files)  Logs should be on a separate disk from data files  Ideally separate system and user DBs  If shared instance, put split high utilization DBs onto separate disk devices
  32. 32. Shared Environment vs Dedicated Environment
  33. 33. SANs are Multi-Tenant  You don’t want to share disks with the Exchange server  File servers are a decent partner for database servers
  34. 34. Test Your SAN  Good free tools available like SQLIO  Never run this on a production server (and warn your SAN admin)
  35. 35. Summary  RAID 0 is bad  Hard Drives will always be the bottleneck  Be nice to your SAN admin—ask for RAID 10  Split your SQL files across many disks  SSDs are fast, but pricey
  36. 36. Questions?
  37. 37. Contact Info  Twitter: @jdanton  Email:  Blog (slides):