CLUSTERING AND AVAILABILITY

1. Chapter 11 CLUSTERING AND AVAILABILITY

2. Chapter 11: CLUSTERING AND AVAILABILITY OVERVIEW • Describe the clustering capabilities of Microsoft Windows Server 2003. • Understand how to create clusters with Windows Server 2003. • Plan a high-availability solution that uses clustering services. • Plan a high-availability solution that uses Network Load Balancing. • Estimate your organization’s availability requirements. • Determine which type of cluster to use for your applications.

3. Chapter 11: CLUSTERING AND AVAILABILITY OVERVIEW (CONTINUED) • Understand the differences among the four Network Load Balancing operational modes • List the steps involved in deploying a Network Load Balancing cluster • Monitor Network Load Balancing using Windows Server 2003 tools • List the shared storage hardware systems supported by Windows Server 2003 • Describe the quorum models you can use in a server cluster • List the steps involved in creating a server cluster • Describe the different types of failover policies you can use with server clusters

4. Chapter 11: CLUSTERING AND AVAILABILITY UNDERSTANDING CLUSTERING

5. Chapter 11: CLUSTERING AND AVAILABILITY CLUSTERING TYPES • Server clusters • Network Load Balancing clusters

6. Chapter 11: CLUSTERING AND AVAILABILITY SERVER CLUSTERS

7. Chapter 11: CLUSTERING AND AVAILABILITY NETWORK LOAD BALANCING

8. Chapter 11: CLUSTERING AND AVAILABILITY NETWORK LOAD BALANCING AND REPLICATION • The key difference between Network Load Balancing and server clustering is that in a Network Load Balancing cluster each system in the cluster maintains its own data set. • Network Load Balancing is unsuitable for applications that have a very fluid data set. • Manual replication of data between nodes in a Network Load Balancing cluster should be occasional, rather than continuous.

9. Chapter 11: CLUSTERING AND AVAILABILITY DESIGNING A CLUSTERING SOLUTION • What are you protecting against? • Software failure • Hardware failure • Site failure

10. Chapter 11: CLUSTERING AND AVAILABILITY ESTIMATING AVAILABILITY REQUIREMENTS • The degree of availability you require depends on a variety of factors: • Nature of the applications you are running • Size, location, and distribution of your user base • Role of the applications in your organization

11. Chapter 11: CLUSTERING AND AVAILABILITY SCALING CLUSTERS • Scale up—Improve performance of systems by installing a more powerful processor, adding random access memory (RAM), and higher-performance disk subsystems. • Scale out—Add servers to the cluster to increase overall processing power.

12. Chapter 11: CLUSTERING AND AVAILABILITY SCALABILITY IN THE REAL WORLD • Scalability of a cluster is limited by the capabilities of the operating system: • Scaling out depends on the clustering limitations of the operating systems used in the cluster. • Scaling up depends on the maximum supported hardware configuration of the operating systems used in the cluster.

13. Chapter 11: CLUSTERING AND AVAILABILITY NUMBERS OF CLUSTERS

14. Chapter 11: CLUSTERING AND AVAILABILITY COMBINING CLUSTERING TECHNOLOGIES

15. Chapter 11: CLUSTERING AND AVAILABILITY DISPERSING CLUSTERS • Geographic separation provides higher availability in situations such as the following: • Natural disaster (flood, earthquake, tornado) • Power failure, rolling blackouts • Theft, vandalism, terrorism

16. Chapter 11: CLUSTERING AND AVAILABILITY USING NETWORK LOAD BALANCING • Easier to install, configure, and maintain than server clustering • Does not require additional storage hardware • Does not require additional software • Managed by using the Network Load Balancing Manager application

17. Chapter 11: CLUSTERING AND AVAILABILITY UNDERSTANDING NETWORK LOAD BALANCING • Each Network Load Balancing cluster can consist of up to 32 servers. • A virtual network adapter acts as an intermediary between the physical network interface and the protocol stack. • Clients address their application requests to the cluster Internet Protocol (IP) address instead of to an individual server’s IP address.

18. Chapter 11: CLUSTERING AND AVAILABILITY NETWORK LOAD BALANCING CLUSTERING AND THE DOMAIN NAME SYSTEM • The Domain Name System (DNS) resource records for systems in a cluster must be changed so that they supply clients with the cluster IP address, not the original server IP addresses. • An algorithm associated with the virtual network adapter determines which requests should be answered and which should be ignored. • All nodes in the cluster receive the request, but only the node whose turn it is actually answers the request.

19. Chapter 11: CLUSTERING AND AVAILABILITY PLANNING A NETWORK LOAD BALANCING DEPLOYMENT • Using Network Load Balancing requires that you create a plan for the infrastructure that will support your cluster servers. • The high availability provided by Network Load Balancing must be further supported by fault-tolerant implementations of other networking equipment. • The security of your cluster servers and the rest of your internal network must be considered during the planning phase.

20. Chapter 11: CLUSTERING AND AVAILABILITY NETWORK LOAD BALANCING OPERATIONAL MODES • Unicast mode—Servers in the cluster can communicate only with each other if more than one network interface is installed in the server. • Multicast mode—Servers with one network card can communicate with each other, but any routers on the network must support multicast Media Access Control (MAC) addresses.

21. Chapter 11: CLUSTERING AND AVAILABILITY NETWORK LOAD BALANCING HEARTBEATS • Servers in a Network Load Balancing cluster determine independently whether to process an incoming request. • Servers in a Network Load Balancing cluster transmit heartbeat messages to let the other servers in the cluster know they are running and operational. • Heartbeats are the only cluster-related communication between servers in a Network Load Balancing cluster.

22. Chapter 11: CLUSTERING AND AVAILABILITY DEPLOYING A NETWORK LOAD BALANCING CLUSTER

23. Chapter 11: CLUSTERING AND AVAILABILITY MONITORING NETWORK LOAD BALANCING • Monitoring Network Load Balancing clusters can be performed using • Network Load Balancing Manager • Event Viewer

24. Chapter 11: CLUSTERING AND AVAILABILITY USING NETWORK LOAD BALANCING MANAGER

25. Chapter 11: CLUSTERING AND AVAILABILITY USING EVENT VIEWER

26. Chapter 11: CLUSTERING AND AVAILABILITY USING Nlb.exe • Command-line utility used to configure and manage Network Load Balancing clusters • Enables commands to be placed into scripts and batch files • Uses the same command options as the WLBS utility provided in earlier versions of Windows server operating systems

27. Chapter 11: CLUSTERING AND AVAILABILITY DESIGINING A SERVER CLUSTER • Designing a server cluster deployment • Planning a server cluster hardware configuration • Creating an application deployment plan • Selecting a quorum model • Creating a server cluster • Configuring failover policies

28. Chapter 11: CLUSTERING AND AVAILABILITY DESIGINING A SERVER CLUSTER DEPLOYMENT

29. Chapter 11: CLUSTERING AND AVAILABILITY PLANNING A SERVER CLUSTER HARDWARE CONFIGURATION • The computers running Windows Server 2003 that you use to build a server cluster must • Use the same edition of the Windows operating system • Use the same processor architecture • Have at least one standard network connection • Have a separate connection to the shared storage device

30. Chapter 11: CLUSTERING AND AVAILABILITY USING SMALL COMPUTER SYSTEM INTERFACE

31. Chapter 11: CLUSTERING AND AVAILABILITY USING FIBRE CHANNEL

32. Chapter 11: CLUSTERING AND AVAILABILITY CREATING AN APPLICATION DEPLOYMENT PLAN • Single-instance applications—Applications that can run on no more than one server at a time, using a given configuration • Multiple-instance applications—Applications in which duplicated code can run on multiple nodes in a cluster or in which the code can be partitioned

33. Chapter 11: CLUSTERING AND AVAILABILITY DEPLOYING SINGLE-INSTANCE APPLICATIONS

34. Chapter 11: CLUSTERING AND AVAILABILITY CAPACITY PLANNING • The servers in your cluster must have sufficient memory and enough processing capabilities to function adequately in a worst-case scenario. • Insufficient capacity planning can negate the benefit of using a cluster. • Testing and evaluation should include peak load tests to simulate realistic use.

35. Chapter 11: CLUSTERING AND AVAILABILITY DEPLOYING MULTIPLE-INSTANCE APPLICATIONS

36. Chapter 11: CLUSTERING AND AVAILABILITY SELECTING A QUORUM MODEL • Single-node cluster • Single-quorum device cluster • Majority node set cluster

37. Chapter 11: CLUSTERING AND AVAILABILITY CREATING A SERVER CLUSTER

38. Chapter 11: CLUSTERING AND AVAILABILITY CLUSTER RESOURCES • A cluster resource is any physical or logical element the Cluster service can manage by bringing it online or offline and moving it to a different node. • Cluster resources supported by server clusters running Windows Server 2003 include storage devices, configuration parameters, scripts, and applications.

39. Chapter 11: CLUSTERING AND AVAILABILITY CONFIGURING FAILOVER POLICIES • Failover pairs • Hot-standby server • N+I • Failover ring • Random

40. Chapter 11: CLUSTERING AND AVAILABILITY SUMMARY • A cluster is a group of servers appearing to users as a single resource that provides high availability, reliability, and scalability for specific applications. • A server cluster is a group of servers running a stateful application, such as a database server, and sharing a common data store. • A Network Load Balancing cluster is a group of servers running a stateless application, each of which has an identical independent data store. • Network Load Balancing works by creating a virtual network adapter with IP and MAC addresses that represent the cluster as a single unit. • Network Load Balancing can be run in either unicast mode or multicast mode.

41. Chapter 11: CLUSTERING AND AVAILABILITY SUMMARY (CONTINUED) • Using multiple adapters in each server in a cluster can prevent network performance degradation. • A server cluster requires a storage resource shared by the nodes in the cluster. • In a server cluster, the quorum is a storage resource that contains cluster configuration data. • You can configure a cluster to use various failover policies. • To create and manage server clusters, you use the Cluster Administrator application. To manage Network Load Balancing clusters, you use Network Load Balancing Manager.