Windows Server 2008 R2 Unleashed (241 page)

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FIGURE 29.17

Specifying the DNS/Internet name associated with an NLB cluster IP address.

10. If multiple IP addresses were defined on the previous page, the IP address can be

chosen from the IP address drop-down list, and the Internet name and cluster opera-

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tion mode can be defined for each additional address. When all the IP addresses

have had their properties defined, click Next to continue.

11. On the Port Rules page, a default rule is precreated that allows all traffic on all ports

to be load-balanced across the NLB cluster between the cluster IP address and the

dedicated IP address of the local server’s dedicated IP address. Select this rule and

click the Remove button to delete it.

12. Click the Add button to create a new port rule.

13. When the Add/Edit Port Rule window opens, type in the starting and ending port

range, for example 80 and 80 for a single HTTP port rule, but do not close the window.

14. Under protocols, select the TCP option button, but do not close the window.

15. In the Filtering Mode section, select Multiple Host, and select Single Affinity, but do

not close the window.

16. Finally, review the settings, and click OK to create the port rule, as shown in

Figure 29.18.

17. Back on the Port Rules page, click the Add button to create an additional port rule.

18. Specify the starting port as 0 and the ending port as 79, select Both for the protocol’s

configuration, select the Disable This Port Range Filtering mode, and click OK to

create the rule.

19. Back in the Port Rules page, click the Add button to create one more port rule.

20. Specify the starting port as 81 and the ending port as 65535, select Both for the

protocol’s configuration, select the Disable This Port Range Filtering mode, and click

OK to create the rule.

Deploying Network Load Balancing Clusters

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FIGURE 29.18

Defining a port rule for TCP port 80 with multiple host, single affinity.

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21. Back on the Port Rules page, review the list of port rules and if the rules look correct,

click Finish.

22. Back in the Network Load Balancing Manager window, the cluster will be created

and brought online. The cluster IP addresses are automatically added to the TCP

properties of the designated network adapter. Close the NLB Manager and log off of

the server.

Adding Additional Nodes to an Existing NLB Cluster

After an NLB cluster is created, additional nodes can be added to it. To add nodes to an

existing cluster, perform the following steps:

1. Log on to the Windows Server 2008 R2 system with an account that has local

administrator rights.

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2. Click Start, click All Programs, click Administrative Tools, and select Network Load

Balancing Manager.

3. When the Network Load Balancing Manager console opens, click the Cluster menu,

and select Connect to Existing.

4. When the Connect page opens, type in the hostname of a cluster node in the cluster

that will have nodes added to it. For this example, the hostname is NODE02. Type

in NODE02 and click Connect to retrieve a list of all NLB clusters running on the

specified host.

5. In the Clusters section of the Connect page, select the cluster that will be loaded

into the management console, and click Next.

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6. Back in the Network Load Balancing Manager window, in the tree pane, select and

right-click the cluster, and select Add Host to Cluster.

7. When the Connect page opens, type in the hostname of the Windows Server 2008

R2 system that will be added to the cluster, and click Connect.

8. After the system is connected, a list of all of the available network adapters is shown.

Select the desired adapter to use for the NLB cluster, and click Next.

9. On the Host Parameters page, review the details of the page, and click Next to

continue. The default settings should be sufficient unless the Host ID needs to be

changed or if multiple IP addresses are already bound to the adapter; select the

desired IP address to use for dedicated NLB cluster communication, and click Next

to continue.

10. On the Port Rules page, the existing port rules for the cluster are listed. Unless this

node will handle different traffic on this cluster, accept the defaults and click Finish.

11. The node will be added to the cluster and if the node addition is successful, both

nodes will be listed under the cluster with a green background, as shown in Figure

29.19.

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FIGURE 29.19

Verifying that all NLB cluster nodes are operating properly.

12. Close the Network Load Balancing Manager and log off of the server.

Managing NLB Clusters

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Managing NLB Clusters

An NLB cluster can be managed using the Network Load Balancing Manager from a local

cluster node or from a remote machine with the Remote Administration tools installed.

Network Load Balancing can also be managed using the command-line tool NLB.exe and

by using some of the new PowerShell commands included with Windows Server 2008 R2.

Using the NLB Manager, a node can be added, removed, or suspended from cluster opera-

tion to perform maintenance, including hardware or software updates. Because data is not

replicated between cluster nodes, any data that is required by all nodes in the cluster

either needs to be replicated to each node or the application needs to be configured to

access data on a system that is not in the NLB cluster.

Backing Up and Restoring NLB Nodes

The procedure for backing up and restoring NLB nodes is no different than for standalone

servers. A full system backup using Windows Server Backup or the organization’s Windows

Server 2008 R2 approved backup software should be created before and after any major

server or NLB cluster configuration changes are implemented. An NLB configuration can

be restored when the System State of a particular node is restored. If a full node recovery is

necessary, the System State and local disks should be restored using a full system restore.

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For detailed backup and restore procedures, refer to Chapters 30 and 31.

Performing Maintenance on an NLB Cluster Node

To perform maintenance on an NLB cluster node, the administrator can temporarily stop

the NLB service on the node in the cluster, perform the upgrade, and start it back up later.

Stopping the cluster node without impacting user connections requires the use of the

Drainstop option from the Network Load Balancing Manager. The Drainstop option

informs the NLB cluster that the particular node will be stopped and no new connections

should be directed toward this node. All existing connections will remain up and running

and when all of the sessions are closed, the NLB service will be shut down on the desig-

nated node. After the maintenance has completed, the NLB service can be restarted on the

NLB node and client connections can be initiated. To perform maintenance on a cluster

node, perform the following steps:

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1. Log on to each Windows Server 2008 R2 system with an account that has local

administrator rights.

2. Click Start, click All Programs, click Administrative Tools, and select Network Load

Balancing Manager.

3. When the Network Load Balancing Manager console opens, click the Cluster menu,

and select Connect to Existing.

4. When the Connect page opens, type in the hostname of a cluster node in the cluster

that has the node that requires maintenance, and click the Connect button. Do not

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type in the name of the node that will be taken down for maintenance as the NLB

manager will lose connections to the cluster.

5. After the system is connected, select the desired NLB cluster and click Finish to

connect to the NLB cluster.

6. In the tree pane, expand the cluster to reveal all of the nodes in the cluster.

7. Locate the node that will be taken offline for maintenance. Right-click the node,

select Control Host, and select Drainstop, as shown in Figure 29.20.

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FIGURE 29.20

Taking an NLB cluster node offline using the Drainstop option.

8. After all connections are closed, the node will be highlighted in red and the status

will be changed to “Host is Stopped.” Perform the necessary maintenance on the

NLB cluster node.

9. After the maintenance has been performed, open NLB Manager, connect to the

cluster, and expand the cluster to reveal the nodes.

10. Select the node that has been stopped, right-click the node, select Control Host, and

select Start.

11. After the host starts up, it will have a green background and will immediately be

ready to accept client connections.

12. Close the Network Load Balancing Manager and log off of the server.

To perform the Drainstop using PowerShell, perform the following steps:

1. Open PowerShell from the Accessories/System Tools folder in the All Programs Start

menu group on a Windows Server 2008 R2 system.

Best Practices

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2. Type the command import-module networkloadbalancingclusters and press Enter.

3. To stop the NLB service on NODE01, using Drainstop as an example, type the

command Stop-NlbClusterNode NODE01 –Drain and press Enter.

4. The PowerShell cmdlet will return the status of the command once the server has

stopped.

5. To resume operation on this node, type the command Start-NlbClusterNode

NODE01 and press Enter.

6. When completed, close the PowerShell window and log off of the server.

To get a list of all PowerShell NLB cmdlets, from within a PowerShell window after

running the import-module command for NLB, type the command Get-Command –Module

NetworkLoadBalancingClusters and press Enter.

Summary

Windows Server 2008 R2 provides two very different clustering technologies that enable

organizations to create system-level fault tolerance and provide high availability for

mission-critical applications and services. Although failover clusters and Network Load

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Balancing are each characteristically different and are best deployed on very different

types of applications, between them they can increase fault tolerance for almost any