5 Prerequisites for Installing Enterprise Manager on Oracle RAC

Configure Oracle Cluster Synchronization Services (CSS)

The first time you install Oracle Enterprise Manager on a system, Oracle Universal Installer configures and starts a single-node version of the Oracle Cluster Synchronization Services (CSS) service. The CSS service is required to enable synchronization between an Automatic Storage Management (ASM) instance and the database instances that rely on it for database file storage. It is configured and started even if you do not choose Automatic Storage Management as a storage mechanism for database files.Because it must be running before any Automatic Storage Management instance or database instance is started, Oracle Universal Installer configures it to start automatically when the system starts.For Oracle RAC installations, the CSS service is installed with Oracle Clusterware in a separate Oracle home directory. For single-node installations, the CSS service is installed in and runs from the same Oracle home as Oracle Database. For this reason, you must use caution when removing Oracle Database software from the system. Before you remove an Oracle home directory that contains Oracle Database, you must either delete the CSS service configuration, or if necessary, reconfigure the CSS service to run from another Oracle home directory.

If you plan to have more than one Oracle Database installation on a single system and you want to use Automatic Storage Management for database file storage, Oracle recommends that you run the CSS service and the Automatic Storage Management instance from the same Oracle home directory and use different Oracle home directories for the database instances.

Certification for Agents on Oracle Real Application Clusters (Oracle RAC)

Additional Software Requirements for Agent Installation on Clusters

If the Enterprise Manager installation is on a cluster, you must install Oracle Clusterware (formerly called Oracle Cluster Ready Services) or any vendor clusterware separately, besides fulfilling all the other Oracle software requirements (see Chapter1, "Enterprise Manager Software Requirements" for more information). Oracle Clusterware is not available on the Oracle Enterprise Manager Grid Control 10g Release 2 (10.2) installation media.

Preinstallation Tasks for Oracle Real Application Clusters

Before you install and use Oracle Real Application Clusters, you must configure secure shell (SSH) for the Oracle user on all cluster nodes. The installer uses the ssh and scp commands during installation to run remote commands on and copy files to the other cluster nodes. You must configure SSH so that these commands do not prompt for a password.

To configure SSH, complete the following steps on each cluster node:

1. Log in as the Oracle user.

2. If necessary, create the .ssh directory in the Oracle user's home directory and set the correct permissions on it:

   $ mkdir ~/.ssh
   $ chmod 755 ~/.ssh
   
   

3. Enter the following commands to generate an RSA key for version 2 of the SSH protocol:

   $ /usr/bin/ssh-keygen -t rsa
   
   

   At the prompts:

   • Accept the default location for the key file.

   • Enter and confirm a password (or pass phrase) that is different from the Oracle user's password.

   This command writes the public key to the ~/.ssh/id_dsa.pub file and the private key to the ~/.ssh/id_dsa file. Never distribute the private key to anyone.

4. Enter the following commands to generate a DSA key for version 2 of the SSH protocol:

   $ /usr/bin/ssh-keygen -t dsa
   
   

   At the prompts:

   • Accept the default location for the key file.

   • Enter and confirm a password (or pass phrase) that is different from the Oracle user's password.

   This command writes the public key to the ~/.ssh/id_dsa.pub file and the private key to the ~/.ssh/id_dsa file. Never distribute the private key to anyone.

5. Copy the contents of the ~/.ssh/id_rsa.pub and ~/.ssh/id_dsa.pub files to the ~/.ssh/authorized_keys file on this node and to the same file on all other cluster nodes.

   Note:

   The ~/.ssh/authorized_keys file on every node must contain the contents from all of the ~/.ssh/id_rsa.pub and ~/.ssh/id_dsa.pub files that you generated on all cluster nodes.

6. Change the permissions on the ~/.ssh/authorized_keys file on all cluster nodes:

   $ chmod 644 ~/.ssh/authorized_keys
   
   

   At this point, if you use ssh to log in to or run a command on another node, you are prompted for the password (or pass phrase) that you specified when you created the DSA key.

To enable the installer to use the ssh and scp commands without being prompted for a password, follow these steps:

1. On the system where you want to run the installer, log in as the Oracle user.

2. Enter the following commands:

   $ exec /usr/bin/ssh-agent $SHELL$ /usr/bin/ssh-add
   
   

3. At the prompts, enter the password (or pass phrase) for each key that you generated.

   If you have configured SSH correctly, you can now use the ssh or scp commands without being prompted for a password or a pass phrase.

4. To test the SSH configuration, enter the following commands from the same session, testing the configuration of each cluster node:

   $ ssh nodename1 'date'$ ssh nodename2 'date'    .    .
   
   

   These commands should display the date set on each node. If any node prompts for a password or pass phrase, verify that the ~/.ssh/authorized_keys file on that node contains the correct public keys.

5. To ensure that X11 forwarding will not cause the installation to fail, create a user-level SSH client configuration file for the Oracle software owner user, as follows:

   1. Using any text editor, edit to create the ~oracle/.ssh/config file.

   2. Ensure the ForwardX11 attribute is set to no, for example:

      Host *
            ForwardX11 no
      
      

6. You must run the installer from this session or remember to repeat steps 2 and 3 before you start the installer from a different session.

Some of the other preinstallation tasks are listed below:

• Configure SSH on all nodes.

• Oracle Clusterware/vendor clusterware must be running.

For more detailed information on these preinstallation and installation tasks that you must perform for an Oracle RAC installation, see Oracle Real Application Clusters Installation and Configuration Guide.