Tag Archives: rac

13: Upgrading and Patching Oracle RAC

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Keeping Oracle Real Application Clusters (RAC) environments up-to-date through upgrades and patching is crucial for maintaining security, performance, and access to the latest features. In this chapter, we’ll cover the process of RAC database upgrades, rolling upgrades, minimizing downtime, and using OPatch for patch management.

1. RAC Database Upgrades: Pre-Upgrade Planning and Steps

Upgrading Oracle RAC involves several important steps, from planning to execution, to ensure a smooth transition with minimal downtime.

Pre-Upgrade Planning
  • Backup: Always take a full backup of your RAC environment before upgrading to safeguard against potential issues.
  • Compatibility Check: Verify compatibility between the current Oracle version and the target version. Use Oracle’s Database Pre-Upgrade Information Tool to check the system.
  • Example Command to Run Pre-Upgrade Checks:
$ORACLE_HOME/jdk/bin/java -jar $ORACLE_HOME/rdbms/admin/preupgrade.jar TERMINAL TEXT

Check Patch Requirements: Ensure that all pre-upgrade patches required by the new version are applied.

Example Command to Check Existing Patches:

opatch lsinventory
Steps to Upgrade Oracle RAC
  1. Step 1: Prepare the Environment
    • Check that all RAC nodes have the necessary storage and OS requirements for the new Oracle version.
    Example Command to Check Space:
df -h

Step 2: Shutdown RAC Instances

  • Use srvctl to stop the Oracle RAC instances on all nodes.

Example Command:

srvctl stop database -d racdb

Step 3: Upgrade the Database

  • Follow the Oracle Database Upgrade Assistant (DBUA) or manual steps to upgrade the database on all RAC nodes.

Example Command to Launch DBUA:

dbua

Step 4: Restart and Verify

  • Once the upgrade completes, restart the RAC instances and verify the upgrade.

Example Command to Start RAC:

srvctl start database -d racdb

Verify Database Version:

SELECT * FROM v$version;

2. Rolling Upgrades and Patching with Oracle RAC

Oracle RAC supports rolling upgrades, which means you can patch or upgrade one node at a time without taking down the entire cluster. This is particularly useful for applying interim patches or upgrading to a new minor version with minimal disruption.

Steps for Rolling Upgrades:
  1. Step 1: Apply Patch on First Node
    • Use OPatch to apply the patch on one node, while the other nodes continue to serve the database.
    Example OPatch Command:
opatch apply

Step 2: Restart the Patched Node

  • After applying the patch on the first node, restart the node to ensure proper patch installation.

Example Command:

srvctl start instance -d racdb -i racdb1
  1. Step 3: Apply Patch to Other Nodes
    • Repeat the patch application and restart process for the remaining nodes.
    This approach minimizes downtime as the database continues to operate on other nodes during the upgrade or patching process.
Benefits of Rolling Upgrades:
  • Minimized Downtime: Only one node is patched at a time, ensuring that the entire RAC system does not go offline.
  • Seamless Patching: Business continuity is maintained as services run on other nodes.

3. Minimizing Downtime During RAC Upgrades

Minimizing downtime during Oracle RAC upgrades is essential for mission-critical systems. In addition to rolling upgrades, several strategies can be used to reduce the impact on operations:

  • Use of Standby Databases: Integrate Oracle Data Guard with RAC to offload critical workloads to a standby database during the upgrade.
  • Parallel Node Patching: For minor patches, consider parallel node patching to reduce the overall upgrade window.
  • Test in a Staging Environment: Before performing the upgrade in production, conduct the upgrade in a staging environment to validate the process and identify potential issues.
  • Example for Switching Between RAC Nodes During Upgrades:
srvctl relocate service -db racdb -service hr_service -oldinst racdb1 -newinst racdb2
  • This command relocates the service from one node to another while applying patches or upgrades.

4. Using OPatch and Patch Sets for RAC

OPatch is the command-line tool provided by Oracle to apply patches and patch sets in Oracle RAC environments. Oracle also releases Patch Set Updates (PSUs) and Bundle Patches to address security vulnerabilities and known bugs.

Applying a Patch with OPatch:
  1. Step 1: Download the Patch:
    • Download the required patch from Oracle Support.
  2. Step 2: Check Patch Conflicts:
    • Before applying, check for conflicts using opatch.
    Example Command:
opatch prereq CheckConflictAgainstOHWithDetail -ph ./

Step 3: Apply the Patch:

  • Use the opatch apply command to apply the patch on each RAC node.

Example Command:

opatch apply

Step 4: Verify Patch Application:

  • After applying the patch, check the patch inventory.

Example Command:

opatch lsinventory
Example of Using OPatch for Patch Sets:

Patch sets are larger sets of cumulative patches, typically addressing a broader set of issues than individual patches.

  • Patch Installation Example
opatch apply -oh $ORACLE_HOME -id <patch_number>

5. Best Practices for RAC Upgrades and Patch Management

To ensure smooth upgrades and patches in an Oracle RAC environment, follow these best practices:

  • Plan and Test: Always plan and test your upgrades and patches in a non-production environment before applying them in production.
  • Backup Before Patching: Always take full database backups and, if possible, system snapshots before applying patches.
  • Example Command to Backup RAC Database:
rman target /
BACKUP DATABASE PLUS ARCHIVELOG;
  • Monitor System Health: After applying patches or upgrading, monitor the system for any anomalies or performance issues using Oracle Enterprise Manager (OEM) or custom monitoring scripts.
  • Stay Informed: Regularly check Oracle’s security alerts and patch documentation to ensure your system remains secure and up-to-date.

Conclusion

Upgrading and patching Oracle RAC requires careful planning, testing, and execution. Using rolling upgrades and OPatch helps minimize downtime, making it possible to perform necessary maintenance while keeping critical systems online. Following best practices for patch management and upgrades ensures a smooth and secure process.