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SERVER CLUSTERING

Chapter 6

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OVERVIEW

List the types of server clusters.

Determine which type of cluster to use for your applications.

Describe how Network Load Balancing and server clusters work.

Deploy an NLB cluster.

Deploy a server cluster.

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WINDOWS SERVER 2003 CLUSTER TYPES

Server clusters

Network Load Balancing clusters

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SERVER CLUSTERS

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NETWORK LOAD BALANCING

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DESIGNING A CLUSTERING SOLUTION

What are you protecting against? Software failure

Hardware failure

Site failure

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ESTIMATING AVAILABILITY REQUIREMENTS

Decide what applications are required, and how much downtime can be tolerated.

Consider what threats may be present—they will not be the same in every situation or environment.

Investment in fault tolerance and availability is governed by the laws of diminishing returns. Spending twice as much will not provide double the protection.

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SCALING CLUSTERS

Scale up

Improve performance of systems by installing a more powerful processor and adding RAM and higher performance disk subsystems.

Scale out

Add servers to cluster to increase overall processing power.

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HOW MANY CLUSTERS?

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COMBINING CLUSTERING TECHNOLOGIES

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DISPERSING CLUSTERS

Geographic separation provides higher availability in situations such as: Natural disaster (flood, earthquake, tornado)

Power failure, rolling blackouts

Theft, vandalism, terrorism

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USING NETWORK LOAD BALANCING

Easier to install, configure, and maintain than server clustering.

Does not require additional storage hardware.

No additional software is required.

Managed via the Network Load Balancing Manager application.

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UNDERSTANDING NETWORK LOAD BALANCING

Each NLB 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.

An algorithm associated with the virtual network adapter determines which requests should be answered and which should be ignored.

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PLANNING A NETWORK LOAD BALANCING DEPLOYMENT

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NLB OPERATIONAL MODES

Unicast mode

Servers in the cluster can only communicate 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 MAC addresses.

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NLB NETWORKING

Servers in an NLB cluster determine independently whether or not to process an incoming request.

Servers in an NLB 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 an NLB cluster.

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DEPLOYING A NETWORK LOAD BALANCING CLUSTER

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MONITORING NETWORK LOAD BALANCING

Monitoring of NLB clusters can be performed using: Network Load Balancing Manager

Event Viewer

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USING NETWORK LOAD BALANCING MANAGER

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USING EVENT VIEWER

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USING NLB.EXE

Command line utility used to configure and manage NLB clusters

Enables commands to be placed into scripts and batch files

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DESIGNING 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

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DESIGNING A SERVER CLUSTER DEPLOYMENT

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PLANNING A SERVER CLUSTER HARDWARE CONFIGURATION

All servers in the cluster must be running the same edition of Windows Server 2003.

All servers in the cluster must have the same processor architecture: 32-bit or 64-bit.

At least one network interface per system is required. Two are preferred.

Shared storage connection is required.

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USING SCSI

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USING FIBRE CHANNEL

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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

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DEPLOYING SINGLE-INSTANCE APPLICATIONS

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CAPACITY PLANNING

Idle servers in a standby configuration must be capable of running the application(s) on the active server.

Depending on the failover configuration, the idle server may be required to run more than one application in the event of a multiple server failure.

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DEPLOYING MULTIPLE-INSTANCE APPLICATIONS

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SELECTING A QUORUM MODEL

Single-node cluster

Single-quorum device cluster

Majority node set cluster

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CREATING A SERVER CLUSTER

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CONFIGURING FAILOVER POLICIES

Failover pairs

Hot-standby server

N+I

Failover ring

Random

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CHAPTER SUMMARY

A cluster is a group of servers that appears to users as a single resource and that provides high availability, reliability, and scalability for specific applications.

A Network Load Balancing cluster is a group of servers running a stateless application, such as a Web server, each of which has an identical, independent data store.

A server cluster is a group of servers running a stateful application, such as a database server, and sharing a common data store.

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CHAPTER SUMMARY (continued)

Network Load Balancing works by creating a virtual network adapter with IP and MAC addresses that represent the cluster as a single unit.

When NLB is running in unicast mode, ordinary communication between cluster servers is impossible. In multicast mode, the cluster servers can communicate normally.

Although NLB and server clusters can both function with a single network interface adapter installed in each server, using multiple adapters in each server can prevent network performance degradation.

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CHAPTER SUMMARY (continued)

A server cluster requires a storage resource shared by the nodes in the cluster. Windows Server 2003 supports shared SCSI and Fibre Channel for this purpose.

In a server cluster, the quorum is a storage resource that contains cluster configuration data, which nodes use to create their configuration databases as they join the cluster.

You can configure a cluster to use various failover policies by specifying which nodes are permitted to run various cluster resources.

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CHAPTER SUMMARY (continued)

To create and manage server clusters, use the Cluster Administrator application. To manage Network Load Balancing clusters, use Network Load Balancing Manager.