11 CLUSTERING AND AVAILABILITY Chapter 11

Chapter 11: CLUSTERING AND AVAILABILITY2 OVERVIEW  Describe the clustering capabilities of Microsoft Windows Server  Understand how to create clusters with Windows Server  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.  Describe the clustering capabilities of Microsoft Windows Server  Understand how to create clusters with Windows Server  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.

Chapter 11: CLUSTERING AND AVAILABILITY3 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  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

Chapter 11: CLUSTERING AND AVAILABILITY4 UNDERSTANDING CLUSTERING

Chapter 11: CLUSTERING AND AVAILABILITY5 CLUSTERING TYPES  Server clusters  Network Load Balancing clusters  Server clusters  Network Load Balancing clusters

Chapter 11: CLUSTERING AND AVAILABILITY6 SERVER CLUSTERS

Chapter 11: CLUSTERING AND AVAILABILITY7 NETWORK LOAD BALANCING

Chapter 11: CLUSTERING AND AVAILABILITY8 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.  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.

Chapter 11: CLUSTERING AND AVAILABILITY9 DESIGNING A CLUSTERING SOLUTION  What are you protecting against?  Software failure  Hardware failure  Site failure  What are you protecting against?  Software failure  Hardware failure  Site failure

Chapter 11: CLUSTERING AND AVAILABILITY10 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  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

Chapter 11: CLUSTERING AND AVAILABILITY11 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.  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.

Chapter 11: CLUSTERING AND AVAILABILITY12 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.  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.

Chapter 11: CLUSTERING AND AVAILABILITY13 NUMBERS OF CLUSTERS

Chapter 11: CLUSTERING AND AVAILABILITY14 COMBINING CLUSTERING TECHNOLOGIES

Chapter 11: CLUSTERING AND AVAILABILITY15 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  Geographic separation provides higher availability in situations such as the following:  Natural disaster (flood, earthquake, tornado)  Power failure, rolling blackouts  Theft, vandalism, terrorism

Chapter 11: CLUSTERING AND AVAILABILITY16 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  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

Chapter 11: CLUSTERING AND AVAILABILITY17 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.  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.

Chapter 11: CLUSTERING AND AVAILABILITY18 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.  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.

Chapter 11: CLUSTERING AND AVAILABILITY19 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.  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.

Chapter 11: CLUSTERING AND AVAILABILITY20 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.  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.

Chapter 11: CLUSTERING AND AVAILABILITY21 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.  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.

Chapter 11: CLUSTERING AND AVAILABILITY22 DEPLOYING A NETWORK LOAD BALANCING CLUSTER

Chapter 11: CLUSTERING AND AVAILABILITY23 MONITORING NETWORK LOAD BALANCING  Monitoring Network Load Balancing clusters can be performed using  Network Load Balancing Manager  Event Viewer  Monitoring Network Load Balancing clusters can be performed using  Network Load Balancing Manager  Event Viewer

Chapter 11: CLUSTERING AND AVAILABILITY24 USING NETWORK LOAD BALANCING MANAGER

Chapter 11: CLUSTERING AND AVAILABILITY25 USING EVENT VIEWER

Chapter 11: CLUSTERING AND AVAILABILITY26 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  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

Chapter 11: CLUSTERING AND AVAILABILITY27 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  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

Chapter 11: CLUSTERING AND AVAILABILITY28 DESIGINING A SERVER CLUSTER DEPLOYMENT

Chapter 11: CLUSTERING AND AVAILABILITY29 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  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

Chapter 11: CLUSTERING AND AVAILABILITY30 USING SMALL COMPUTER SYSTEM INTERFACE

Chapter 11: CLUSTERING AND AVAILABILITY31 USING FIBRE CHANNEL

Chapter 11: CLUSTERING AND AVAILABILITY32 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  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

Chapter 11: CLUSTERING AND AVAILABILITY33 DEPLOYING SINGLE-INSTANCE APPLICATIONS

Chapter 11: CLUSTERING AND AVAILABILITY34 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.  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.

Chapter 11: CLUSTERING AND AVAILABILITY35 DEPLOYING MULTIPLE-INSTANCE APPLICATIONS

Chapter 11: CLUSTERING AND AVAILABILITY36 SELECTING A QUORUM MODEL  Single-node cluster  Single-quorum device cluster  Majority node set cluster  Single-node cluster  Single-quorum device cluster  Majority node set cluster

Chapter 11: CLUSTERING AND AVAILABILITY37 CREATING A SERVER CLUSTER

Chapter 11: CLUSTERING AND AVAILABILITY38 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.  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.

Chapter 11: CLUSTERING AND AVAILABILITY39 CONFIGURING FAILOVER POLICIES  Failover pairs  Hot-standby server  N+I  Failover ring  Random  Failover pairs  Hot-standby server  N+I  Failover ring  Random

Chapter 11: CLUSTERING AND AVAILABILITY40 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.  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.

Chapter 11: CLUSTERING AND AVAILABILITY41 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.  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.