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    Oracle RAC Clusterware - When are clusterware components created?

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    Geoffrey
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    Oracle RAC Clusterware - When are clusterware components created?

    Post  Geoffrey on Thu Mar 18, 2010 6:54 pm

    After fulfilling the pre-installation requirements, the basic installation steps to follow are:

    1. Invoke the Oracle Universal Installer (OUI)

    2. Enter the different information for some components like:
    - name of the cluster
    - public and private node names
    - location for OCR and Voting Disks
    - network interfaces used for RAC instances
    -etc.

    3. After the Summary screen, OUI will start copying under the $CRS_HOME (this is the $ORACLE_HOME for Oracle Clusterware) in the local node the libraries and executables.
    - here we will have the daemons and scripts init.* created and configured properly.

    Oracle Clusterware is formed of several daemons, each one of which have a special function inside the stack. Daemons are executed via the init.* scripts (init.cssd, init.crsd and init.evmd).

    - note that for CRS only some client libraries are recreated, but not all the executables (as for the RDBMS).

    4. Later the software is propagated to the rest of the nodes in the cluster and the oraInventory is updated.

    5. The installer will ask to execute root.sh on each node. Until this step the software for Oracle Clusterware is inside the $CRS_HOME.

    Running root.sh will create several components outside the $CRS_HOME:

    - OCR and VD will be formated.

    - control files (or SCLS_SRC files ) will be created with the correct contents to start Oracle Clusterware.

    These files are used to control some aspects of Oracle Clusterware like:
    - enable/disable processes from the CSSD family (Eg. oprocd, oslsvmon)
    - stop the daemons (ocssd.bin, crsd.bin, etc).
    - prevent Oracle Clusterware from being started when the machine boots.
    - etc.

    - /etc/inittab will be updated and the init process is notified.

    In order to start the Oracle Clusterware daemons, the init.* scripts first need to be run. These scripts are executed by the daemon init. To accomplish this some entries must be created in the file /etc/inittab.

    - the different processes init.* (init.cssd, init.crsd, etc) will start the daemons (ocssd.bin, crsd.bin, etc). When all the daemons are running then we can say that the installation was successful

    - On 10.2 and later, running root.sh on the last node in the cluster also will create the nodeapps (VIP, GSD and ONS). On 10.1, VIPCA is executed as part of the RAC installation.

    6. After running root.sh on each node, we need to continue with the OUI session. After pressing the 'OK' button OUI will include the information for the public and cluster_interconnect interfaces. Also CVU (Cluster Verification Utility) will be executed.

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