4
Cluster Management

4.1 Cluster Group and Cluster Alias

The cluster alias is a node-independent network name that identifies a cluster and is used for cluster-related system management. MSCS creates a group called Cluster Group (which you can view in MSCS Cluster Administrator), and the cluster alias is the virtual address of this group. Oracle Services for MSCS is a resource in the Cluster Group, making it highly available. This ensures that Oracle Services for MSCS is always available to coordinate Oracle Real Application Clusters Guard processing on all cluster nodes.

In an Oracle Real Application Clusters Guard environment, the cluster alias is used only for system management. Oracle Real Application Clusters Guard Manager interacts with the cluster components and MSCS using the cluster alias.

When you populate the tree view in Oracle Real Application Clusters Guard Manager, you specify the cluster alias, as shown in Figure 4-1. (Note that the manager is labeled "Oracle Fail Safe Manager" until you connect to a cluster that is running Oracle Real Application Clusters Guard.) The cluster alias is not the same as the name of any node in the cluster. By specifying the cluster alias when you add a cluster to the tree view, you ensure that when Oracle Real Application Clusters Guard Manager connects to that cluster it will be using the virtual server where Oracle Services for MSCS is running; the cluster alias is always in the Cluster Group (the same group as Oracle Services for MSCS). See the online help available with Oracle Real Application Clusters Guard Manager for detailed instructions on adding clusters to the tree view and connecting to clusters.

Client applications do not use the cluster alias when communicating with virtual servers. Rather, clients use the virtual address of the group configured for their application.

4.2 Allocating IP Addresses for Virtual Addresses

When you set up a cluster, allocate at least the following number of IP addresses:

• One IP address for each cluster node

• One IP address for the cluster alias

• One IP address for each virtual server (group)

For example, a four-node cluster with an instance group on each node requires nine IP addresses: one for each of the four cluster nodes, one for each of the four instance groups (virtual servers), and one for the cluster alias.

See the Oracle Real Application Clusters Guard Installation Guide for more information about allocating IP addresses for your Oracle Real Application Clusters Guard environment.

4.3 Managing Cluster Security

To accomplish administrative tasks associated with Oracle Real Application Clusters Guard, you need the appropriate privileges to run and use Oracle Services for MSCS and Oracle Real Application Clusters Guard Manager. See the following sections for a detailed description of the requirements for each of the following:

• Oracle Services for MSCS (Section 4.3.1)

• Oracle Real Application Clusters Guard Manager (Section 4.3.2)

4.3.1 Oracle Services for MSCS

To ensure that only users who have the correct privileges can manage resources in a cluster, Oracle Real Application Clusters Guard implements a security component.

Oracle Services for MSCS runs as a Windows service that must run under a domain user account (not the system account) that has Administrator privileges on all cluster nodes. You specified this user account for Oracle Services for MSCS when you installed Oracle Real Application Clusters Guard. (See the Oracle Real Application Clusters Guard Installation Guide for more information about this part of the installation.)

Oracle Real Application Clusters Guard also has its own security component. Therefore, if you make changes to the Windows user account (user name, password, or domain) used by Oracle Services for MSCS, you must also update the security settings for both the Windows service and Oracle Real Application Clusters Guard. Oracle Real Application Clusters Guard provides a Security Setup tool to update this security information.

4.3.1.1 Account Updates Using the Oracle Services for MSCS Security Setup Tool

Oracle Real Application Clusters Guard provides a Security Setup tool that you can use to update the information for the account under which Oracle Services for MSCS runs. The Oracle Services for MSCS Security Setup tool is installed when you install Oracle Real Application Clusters Guard.

On a cluster node, access the Oracle Services for MSCS Security Setup tool from the Windows taskbar, as follows:

Start -> Programs -> <Oracle_Home> -> Oracle Services for MSCS Security Setup

Note: Be sure that you use the Oracle Services for MSCS Security Setup tool to update the security information on all cluster nodes and that you use the same account on all cluster nodes.

Figure 4-2 shows the setup for user account Administrator in the domain NEDCDOMAIN.

Figure 4-2 Windows User Account Settings for the Oracle Services for MSCS

Description of the illustration security.gif

4.4 Using a Multiple Oracle Homes Environment

Oracle Real Application Clusters Guard supports the multiple Oracle homes feature (multiple Oracle homes became available beginning with Oracle8 release 8.0.4). The following list describes the requirements for using Oracle Real Application Clusters Guard in a multiple Oracle homes environment:

• You can install Oracle Services for MSCS in any one Oracle home on all cluster nodes. Only one version of Oracle Services for MSCS can be installed and running on a node.

• Each database to be configured must be installed in the same Oracle home on all cluster nodes that are possible owners. The Verify Cluster operation will validate this symmetry. See Section 6.1.1 for information on the Verify Cluster operation.