• Do we need user equivalence for normal operation of ORacle Real Application Cluster?
    Post By: admin

NO, user equivalence is not required for normal functioning of Oracle Real Application Clusters BUT must be configured for the installation of Oracle software and patches in the Oracle Real Application Cluster environment.

  • How to migrate the single instance database to Oracle Real Application Cluster database?
    Post By: admin

Without going into much details of the steps, the overall simple approach if you can afford downtime would be:

  1. Configure the shared storage to place the Oracle data files and Oracle Cluster files such as OCR and Voting disk.
  2. Install the Oracle Clusterware on all the cluster nodes
  3. Install the Oracle RDBMS software
  4. Create one UNDO tablespace for each target database instance in the existing single instance database.
  5. Configure the cluster database related parameters such as CLUSTER_DATABASE, UNDO_TABLESPACE, REMOTE_LISTENER, THREAD and INSTANCE_NUMBER in the target database initialization parameter file.
  6. Shutdown the single database instance and move the data files to the shared storage
  7. Recreate the control file with the value of MAXINSTANCES parameter grater than the number of actual database instances in the cluster.
  8. Start the first database instance in the new cluster environment and execute the catclust.sql from $ORACLE_HOME/rdbms/admin as sysdba.
  9. Create one redo thread for each database instance in the cluster database and set the instance specific parameter THREAD accordingly for each database instance.
  10. If you want to manage the cluster database instances through Oracle Clusterware, add the cluster database including all the cluster database instances in the OCR using SRVCTL command. Please refer to Oracle Clusterware Quick How Guide under Library section OR you can access the guide directly here


  • What is OCR in Oracle Real Application Cluster?
    Post By: admin

OCR is Oracle Cluster Registry file that Oracle Clusterware use to keep and record the information about the registered Oracle Cluster Resources.

For example when DBA adds a new cluster database/database instance in the Oracle Real Application Cluster using the SRVCTL command, SRVCTL commands internally create and records the cluster resource for the database/database instance.

  • Do I need third party cluster software such as VERITAS, Sun Cluster to build Oracle 10g Real Application Cluster environment?
    Post By: admin

Regardless of third party cluster software, you will have to install the Oracle Clusterware to build the Oracle 10g Real Application Cluster database. Oracle 10g does not require any third party cluster software until there is another application process on the same database server that requires third party cluster software to fail over. In some case you may require third party cluster software if you want to use the cluster file system to place the Oracle data files BUT Oracle do provide the Automatic Storage Management using the Oracle ASM, with no extra cost and very easy to use and manage so you would rarely require third party cluster software if you are using the Oracle 10g Real Application Cluster for the database server only.
Oracle Database 10g Release 2, Oracle Clusterware can be used to manage application processes in the cluster SO why to spend extra money on third party cluster when Oracle is providing everything you need for a cluster database with no extra cost?

  • Can Oracle 10g Real Application Clusters have heterogeneous platforms in cluster?
    Post By: admin

NO, all the cluster nodes must be binary compatible and running on same operating system BUT cluster nodes with different sizes are allowed.

  • How many Network Interface Cards are required on each cluster host to build the Oracle 10g Real Application Clusters?
    Post By: admin

As a minimum requirement, you would require one Network Interface Card (NIC) for your public network and one NIC for private network between the cluster hosts. Typically in production environments to achieve the high availability and to meet the SLA, it is recommended to install redundant NICs for public and private network.

  • Why do I get error 'o2cb_ctl: Unable to load cluster configuration file "/etc/ocfs2/cluster.conf"' while starting the cluster service for Oracle ocfs2? I have checked the cluster.conf file and everything looks fine to me.
    Post By: admin

You should always use ocfs2console to configure the ocfs2 and O2CB cluster service. Sometime it has been observed that even improper indentation in the cluster.conf file when configured manually, can cause this error.

  • How to display the name of cluster in Oracle Clusterware 10g and onwards?
    Post By: admin

Executing the following command :- $CRS_HOME/bin/cemutlo -n should display the cluster information.

  • Can I run Oracle 10g Real Application Cluster database with Oracle Clusterware 11g?
    Post By: admin

Yes, technically there should not be any problem to run Oracle 10g RAC database with Oracle 11g Clusterware because Oracle Clusterware will be on highest level in this case.

  • How many Oracle databases (including cluster database) I can run in a single cluster?
    Post By: admin

here is no limit on number of Oracle databases, you can run in a single cluster. You can run as many Oracle databases as you want including the cluster databases in a single cluster as long as OS resources such as CPU, Network bandwidth and memory are available on the machines in the cluster.