11g Clusterware and ASM Rolling Upgrades Oracle 11g New Features Tips by Donald BurlesonJune 29, 2015

Oracle 11g New Features Tips

Oracle Clusterware can now be upgraded in a rolling fashion, with only one node going down at a time. Performing a rolling Clusterware upgrade is much like performing a standard upgrade, except that only services on the nodes will be stopped that are needed to be patched.  For instance, in a four node cluster,  the nodes can be upgraded two at a time, with the first iteration of the rolling process taking down nodes 1 and 2.

In this situation, first stop all services on the nodes that need to be taken offline.  This can be done using the srvctl utility.

srvctl stop instance ?d dbname ?i instance_name
srvctl stop asm ?n nodename
srvctl stop nodeapps ?n nodename

Run these commands to stop all instances, ASM, and Clusterware on the nodes that are desired to be upgraded.  For example, for a node called ?dbprod1? with a database named ?dbp?:

srvctl stop instance ?d dbp ?i dbp1
srvctl stop asm ?n dbprod1
srvctl stop nodeapps ?n dbprod1

Once the nodes that are to be upgraded have all Oracle services halted, proceed with the upgrade process.  On each node being upgraded, it is important to run the preupdate.sh script as the root user:

$ORA_CRS_HOME/upgrade/preupdate.sh ?crshome $ORA_CRS_HOME ?crsuser crs

Once the preupdate.sh script has been completed, invoke the Oracle Universal Installer (OUI) to upgrade Clusterware on the prepared nodes.  When prompted, choose only the nodes that have been prepared for the rolling upgrade, and follow all on-screen directions to complete the patch.  This includes running $ORA_CRS_HOME/install/rootupgrade.sh once the software update has completed.

ASM Rolling Upgrades

Beginning in Oracle 11gR1, ASM versions can differ for the purpose of rolling upgrades (version greater than or equal to 11.1).  Note that this is meant to be a temporary state, and all nodes should be upgraded to the latest release as quickly as possible.

First, fully upgrade the Clusterware to the new release on all nodes before attempting to perform a rolling upgrade of ASM.  Once the Clusterware has been upgraded,  place the ASM instance into rolling upgrade mode with the following command:

alter system start rolling migration to x.x.x.x.x;

Replace ?x.x.x.x.x? with the version to which the ASM instance will be migrating.  For instance:

alter system start rolling migration to 11.2.0.0.0;

At this point, it is best to shut down each individual ASM instance, upgrade to the latest version, and start the ASM instance to rejoin the cluster.  Do this for each node in the cluster.

It is important to note that the upgrade will fail if there are any rebalance operations currently being performed.  This means avoiding adding or removing disks from the ASM disk groups before performing a rolling upgrade of ASM software.

Once the rolling upgrade is finished, stop the rolling upgrade process with the following command:

alter system stop rolling migration;

If, for any reason ASM must be downgraded, it can be done in a rolling fashion with the same commands.  Downgrade to the lowest version currently in use in the cluster.

Example:  There is a three node RAC cluster.  Two nodes have been upgraded to Oracle 11.2.0.0.0.  One node remains on Oracle 11.1.0.0.0.  Issue the following command on the upgraded nodes:

alter system start rolling migration to 11.1.0.0.0;

Once this command has been run, downgrade the patch and rejoin the cluster.  End the rolling migration with the same command previously mentioned:

alter system stop rolling migration;

Conclusion

Oracle 11g's new features for high availability make RAC a more manageable solution.  A DBA can now properly manage connections across their RAC instances from a multitude of client sources, clone entire RAC configurations, and upgrade with ease.

In addition, with tools like ADDM extending their use to include RAC, a DBA will not be ?in the dark? when trying to locate and fix issues that could be affecting the entire cluster as a whole.  Coupled with other new features available in Oracle 11g, Oracle's high availability offering can be a very powerful addition to the database architecture.