Clustering is very important technology for High Availability and it is important for DBA to understand benefits and pitfalls. With very few available techniques and a lot of gray areas right decision might help to avoid extra costs. Presentation is unveiling clustering basics, reviews and compares clustering technologies including Microsoft, XCOTO Gridscale, and HP PolyserveMatrix. This presentation can be helpful not only to beginners but to intermediate level DBAs and infrastructure managers.

1. Available Clustering Technologies Alexander Prusakov Senior SQL Server DBA June, 2010

2. Consultant - Sr. MS SQL Server DBA 20+ years of IT experience (business users, ERPs, databases and applications support, software development, data warehousing, etc.) 10+ years of experience with MS SQL Server and RDBMS MBA, MCITP: DBA 2005/2008, IndyPASS, IndyNDA, IIBA member Industries: banking/finance, energy, education, health care, manufacturing, IT consulting. Speaker’s Background:

3. What we are talking about and why What is clustering: pure theory Clustering with Microsoft, HP, and others Pluses and minuses Conclusion Q&A Agenda:

4. Target: Hardware failure Database availability Improve hardware quality Duplicate components Duplicate servers Mirroring Log shipping Clustering

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7. A group of buildings and especially houses built close together on a sizable tract in order to preserve open spaces larger than the individual yard for common recreation

8. An aggregation of stars or galaxies that appear close together in the sky and are gravitationally associatedMerriam-Webster Online.21 October 2009

9. What we are talking aboutand why

10. IMPORTANT! Clustering is different from mirroring and/or replication;

11. What is clustering: pure theory Cluster (computing) - is a group of linked computers, working together closely so that in many respects they form a single computer. Clusters are usually deployed to improve performance and/or availability over that provided by a single computer. (From Wikipedia) Cluster categorizations Load-balancing clusters - clusters operate by distributing a workload evenly over multiple back end nodes. Compute clusters - are used for primarily computational purposes, rather than handling IO-oriented operations such as web service or databases. For instance, a cluster might support computational simulations of weather or vehicle crashes. The primary distinction within compute clusters is how tightly-coupled the individual nodes are. Grid computing - usually compute clusters, but more focused on throughput like a computing utility rather than running fewer, tightly-coupled jobs. Often, grids will incorporate heterogeneous collections of computers, possibly distributed geographically distributed nodes, sometimes administered by unrelated organizations. High-availability (HA) clusters – (also known as failover clusters) are implemented primarily for the purpose of improving the availability of services. They operate by having redundant nodes to eliminate single points of failure. Two nodes is the minimum requirement to provide redundancy.

12. What is clustering: pure theory (cont) Cluster members are relatively close; Hardware capabilities are important; SCSI/iSCSI or Fiber drives only; No dynamics disks; MS DTC and Quorum – must exist (with size at least 1Gb each) Two network cards: Local – health check (LooksAlive test) Public – access point

14. Nodeis physical computer with its own IP address, OS, applications.Examples: MS SQL Server cluster – high availability Scale up Federation Oracle Real Application Cluster – load balancing Scale out Scale up

15. High-availability (HA) cluster:

16. IMPORTANT! Cluster is a way to reduce risk of failure: Storage (if it is not clustered itself): Power failure; Storage hardware failure; Geographical location: Disaster (fire, flood, earthquake); Power outage 2003 (New York, Cleveland, Ohio, Detroit, Michigan, Toronto and Ottawa); User’s mistake: From database drop to network cable pull out; Probability of simultaneous hardware failure is not zero.

17. Downtime

18. Probability of failure Mathematic theory. Murphy's law: Anything that can possibly go wrong, does Too many, too close (hardware, software, network, humans…) "Every program has at least one bug and can be shortened by at least one instruction — from which, by induction, it is evident that every program can be reduced to one instruction that does not work." by Ken Arnold

19. Money, money, money Time is money More hardware means more money More software means more money More hardware and/or software means more money Does it worth to go all the way?

20. Cluster configuration Active/Passive — Provides a fully redundant instance of each node, which is only brought online when its associated primary node fails. Active/Active — Traffic intended for the failed node is either passed onto an existing node or load balanced across the remaining nodes. N+1 — Provides a single extra node that is brought online to take over the role of the node that has failed. N+M — In cases where a single cluster is managing many services, having only one dedicated failover node may not offer sufficient redundancy. In such cases, more than one (M) standby servers are included and available. N-to-1 — Allows the failover standby node to become the active one temporarily, until the original node can be restored or brought back online, at which point the services or instances must be failed-back to it in order to restore High Availability. N-to-N — A combination of Active/Active and N+M clusters.

21. Load-balanced (LB) cluster:

25. IMPORTANT! Clustering on virtual servers might not protect from hardware failure. Adds complexity of sizing

26. Compare direct costs * - pricing details have to be complained to Microsoft Licensing

28. 4 processors

29. Native clustering

30. Microsoft Clustering for Enterprise Edition 2005:

31. OS limited ## of CPUs;

32. Partitioning;

33. Parallel index operations;

34. On-line indexing;

36. Key features: Microsoft Clustering for Enterprise Edition 2008: Policy-Based Management; Performance Data Collection; Data Compression; Backup Compression; Resource Governor; Transparent Data Encryption; External Key Management / Extensible Key Management;

37. Key features: Microsoft Clustering for Enterprise Edition 2008 (continue): Data Auditing; Server Group Management; Hot-Add CPUs and Hot-Add Memory; Streamlined Installation; Upgrade Advisor; Partition Aligned Indexed Views; Extended Events; More, more, and more…;

38. Key features: HP PolyServe Matrix with MS SQL Server Standard Edition Non-NTFS file system; Increase disk size dynamically (no limits on disk size/RPM); Usage of files over 2Tb in size (16Tb limit); No need in identical hardware (Be careful!!!); Any SQL instance can be moved to any note; Software monitoring; Dynamic Re-hosting; 4 or 8 Kb disk segment size; Performance cost: 10% ?

39. Key features: XkotoGridscale: Horizontal scalability ~ 0.85*n-servers; Cost ~ 30% in software and hardware (SAN costs are not included); Ability to test new database versions in real production environment; Storage redundancy ; Flexibility; Time stamps?

40. How Microsoft works:

43. Windows cluster:

44. How PolyServe works: What happens during failover: Removes the IP address for the Virtual SQL Server from the original node and then adds it to the backup node; Updates registry keys and then starts SQL Server and SQL Agent on the backup node;

45. PolyServe Matrix Management:

46. PolyServe Matrix Disk Management:

47. PolyServe Matrix Disk Management:

48. PolyServe Matrix Disk Management:

49. You get what you paid for: Microsoft: Hardware is very important; Huge advantage in features; You already have it all; Easy to play with; A lot of documentation; A lot of knowledge around; Cheaper labor (more people know).

50. You get what you paid for: HP: HP – is HP (customer support, buyer experience); Costly training and limited ($2500 pp); Limited accessibility to working cluster; Limited resource pull; Limited second opinion option; Clouded future.

51. Think, analyze, think again – it is not black and white; What is the real business need; Create clear business requirements; Do cost – benefit analysis because cost of the solution should be less than benefits from implementation; Negotiate; Create a clear plan; Conclusion:

52. 100% utilization is fiction: 80% per box utilization; N+1 configuration; Do you really like that vendor; Evaluate alternatives (SSD, SST) How good is your SysAdmin; Do not be afraid – clustering is easy; Just Do It! Conclusion (continue):

53. Internet – find your way. http://www.sql-server-performance.com/articles/clustering/clustering_intro_p1.aspx http://en.wikipedia.org/wiki/Computer_cluster Vendor –pushing sales technique. http://www.microsoft.com/windowsserver2003/enterprise/clustering.mspx http://technet.microsoft.com/en-us/magazine/2007.03.sqlclusters.aspx http://h18006.www1.hp.com/products/storage/software/polyserve/support/hp_polyserve.html http://www.xkoto.com/products/gs-sql.php Where to look for more:

54. Email: a_prusakov@yahoo.com Questions & Open Discussion Thank You!