Rolling Upgrade is the process of upgrading a running WebLogic Server cluster with a patch, maintenance pack, or minor release without shutting down the entire cluster or domain. During the rolling upgrade of a cluster, each server in the cluster is individually upgraded and restarted while the other servers in the cluster continue to host your application.
Prior to the WebLogic Server 9.2 release, to upgrade a cluster, you had to either shutdown the entire domain, or install the upgraded server version on a parallel domain on additional hardware and use a load balancer to transfer load from the old domain to the new domain. The rolling upgrade process minimizes downtime and allows you to install a patch, maintenance pack, or minor release while the domain is still running.
The following topics are included:
Support for rolling upgrade was available starting with WebLogic Server 9.2. The scope of rolling upgrade support encompasses installation of patches and maintenance packs as they are made available for WebLogic Server 10.x.
Rolling upgrade is most applicable to a cluster of WebLogic Server instances, however, you can also install updates to a domain of Managed Servers that are not in a cluster. This documentation focuses on installing upgrades in a cluster.
You can also uninstall a patch, maintenance pack, or minor release in a rolling fashion.
You can still upgrade to the latest patch using other strategies including bringing applications down in order to perform WebLogic Server upgrades, and restarting applications after WebLogic Server upgrades are complete. The rolling upgrade process provides you with an option of upgrading a running WebLogic Server cluster without shutting down the entire cluster or domain.
Before you begin the upgrade process, make sure that you take any necessary precautions such as:
Back up your applications, database schema, other application data, and domains.
If required, obtain latest third party plug-ins or components that are compatible with required non-Oracle components. For example, Apache Web Server libraries.
The rolling upgrade process includes stopping the Administration Server, installing the upgrade, restarting the Administration Server, and then doing the same for each managed server in the cluster. See the following sections for more information:
Before you install the WebLogic Server update on a server, you must first shut down the server. Prior to server shutdown, and depending on your environment, you may need to first stop load balancers or Web Servers from sending requests or traffic to the server, complete any pending processes, and then gracefully shut down the server.
You can shut down a Managed Server from the command line, in a WLST script, or from the Administration Console.
From the command line, you can gracefully shut down the server using the Graceful Shutdown command. This command waits for all the in-process work to be completed before shutting down the server or cluster.
For information about using the Graceful Shutdown command, see "shutdown" in Oracle Fusion Middleware WebLogic Scripting Tool Command Reference. For information about how to shut down the Managed Server from the Console, see "Shutdown servers in a cluster" in Oracle Fusion Middleware Oracle WebLogic Server Administration Console Help.
Notes:
Observer the following:When using the WLST shutdown() command, make sure that you are connected to the Managed server instance that you want to stop. For information about using WLST to shut down servers, see "Managing the Server Life Cycle" in Oracle Fusion Middleware Oracle WebLogic Scripting Tool.
Make sure that you stop all server instances that use the same installed WebLogic Server files.
After you stop the running server on your machine, install the maintenance upgrade. For more information, see "Downloading and Applying Patches" in Oracle Smart Update Installing Patches and Maintenance Packs.
There are multiple methods for installing the patch, maintenance pack, or minor release. The following sections provide information about each of these options.
You can use the Smart Update feature to periodically check for available software updates. When you start Smart Update, it checks the version numbers of the products installed (associated with the current BEA Home directory), and then connects to the Oracle Web site to check for available service packs. For more information about installing using Smart Update, see Oracle Smart Update Installing Patches and Maintenance Packs.
In most cases, the maintenance upgrade can be distributed and installed using a script. You can create a mechanism for replicating a specific maintenance level of an Oracle product that is installed on multiple machines. This capability is especially valuable in production environments, in which the distribution of software updates to machines must be implemented in a controlled, reliable, and reproducible manner.
You can use the Smart Update bsu command, which you can use to apply patches, interactively or via script, that have been downloaded into a patch download directory. For more information, see "Using the Command-Line Interface" in Oracle Smart Update Installing Patches and Maintenance Packs.
Silent-mode installation is a way of setting installation configurations only once and then using those configurations to duplicate the installation on many machines. During installation in silent mode, the installation program reads the settings for your configuration from an XML file that you create prior to beginning the installation. The installation program does not display any configuration options during the installation process. Silent installation applies only to maintenance packs and minor version installation. For more information, see "Running the Installation Program in Silent Mode" in the Oracle WebLogic Server Installation Guide.
For complete information about installing Oracle WebLogic products, see Oracle WebLogic Server Installation Guide.
For sample scenarios and best practices during upgrade, see "Best Practices for Distributing Maintenance Updates" in Oracle Smart Update Installing Patches and Maintenance Packs.
After you install the maintenance upgrade, you may need to modify start scripts before you restart your server. For more information, see "Activating Applied Patches in Your Installations and Applications" in Oracle Smart Update Installing Patches and Maintenance Packs. In addition, other post install tasks that you need to do will vary depending on your environment and the type of maintenance that you installed.
For an overview of methods for starting and stopping server instances, see "Starting and Stopping Servers" in Oracle Fusion Middleware Managing Server Startup and Shutdown for Oracle WebLogic Server.
If required, you may need to reconfigure your Web server or load balancer after the server is started so that requests are again sent to the server.
A patch is a file containing a fix or a small number of fixes that you can install using Smart Update. A patch is typically created to fix a software defect. A patch can be installed using Smart Update (recommended) or by referencing the patch at the beginning of the classpath.
A maintenance pack is a group of fixes combined into one file. Maintenance packs can be installed using Smart Update or by downloading an installer from the support Web site. Both maintenance packs and patches are applied to an existing installation.
While the WebLogic Server domain is running, follow these steps:
Shutdown the Administration Server. For more information, see Quiescing and Stopping Servers.
On the machine that hosts the Administration Server, install the WebLogic Server patch. For more information, see Installing a Patch, Maintenance Pack, or Minor Version.
Restart the Administration Server. For more information, see Restarting Servers.
For each managed server, you need to do the following tasks in sequence:
Shut down the server as described in Quiescing and Stopping Servers.
Install the software update as described in Installing a Patch, Maintenance Pack, or Minor Version.
Restart the server as described in Restarting Servers.
Note:
You can also modify the start scripts using Smart Update to automate the restart process. For more information, see "Modifying a Start Script" in Oracle Smart Update Installing Patches and Maintenance Packs.You have now completed the upgrade process.
A minor version is a new release that includes fixes and new features. A minor release is installed in a completely new directory. Existing domains from the same release family can be run using the new minor release. WebLogic Server 9.1 and WebLogic Server 9.2 are existing examples of minor versions of WebLogic Server 9.x.
While the WebLogic Server domain is running, follow these steps:
Shut down the Administration Server. For more information, see Quiescing and Stopping Servers.
On the machine that hosts the Administration Server, install the new version of WebLogic Server. For more information about installing Oracle products, see Oracle WebLogic Server Installation Guide.
Update your start scripts for the domain so that the new files are in your classpath.
Update your environment variables, such as JAVA_HOME, MW_HOME, BEA_HOME, and WLS_HOME, to point to the new version of WebLogic Server.
Restart the Administration Server. For more information, see Restarting Servers.
For each managed server, you need to do the following tasks, in sequence:
Stop the server as described in Quiescing and Stopping Servers.
Install the software update as described in Installing a Patch, Maintenance Pack, or Minor Version.
Update your start scripts for the domain so that the new files are in your classpath.
Update your environment variables, such as JAVA_HOME, MW_HOME, BEA_HOME, and WLS_HOME, to point to the new version of WebLogic Server.
Restart the server as described in Restarting Servers.
You can uninstall a patch, maintenance pack, or minor release without shutting down the entire cluster or domain. The following sections provide more information.
At times you may want to uninstall a maintenance upgrade. You can use Smart Update to revert your system installation to an earlier version of the release. For more information, see "Uninstalling Maintenance Packs and Patches" in Oracle Smart Update Installing Patches and Maintenance Packs.
The procedure for uninstalling a patch or maintenance pack is in the opposite order of the rolling upgrade:
On each managed server, you need to do the following tasks:
Stop the server as described in Quiescing and Stopping Servers.
Uninstall the patch or maintenance pack.
For more information, see "Uninstalling Maintenance Packs and Patches" in Oracle Smart Update Installing Patches and Maintenance Packs.
Restart the server as described in Restarting Servers.
After all managed servers have been downgraded, do the following tasks on the Administration Server:
Stop the server as described in Quiescing and Stopping Servers.
Uninstall the patch or maintenance pack.
Restart the server as described in Restarting Servers.
The applied patch or maintenance pack is now uninstalled.
For information about uninstalling a minor release, see "Uninstalling the Software" in the Oracle WebLogic Server Installation Guide.
The procedure is in the opposite order of the rolling upgrade:
On each managed server, do the following tasks:
Stop the server as described in Quiescing and Stopping Servers.
Uninstall the patch or maintenance pack.
For more information, see "Uninstalling the Software" in Oracle WebLogic Server Installation Guide.
Updating the start scripts so that the previous version of WebLogic Server is in the classpath and all environment variables refer to the previous version of WebLogic Server.
Restart the server as described in Restarting Servers.
After all managed servers have been downgraded, do the same steps on the Administration Server:
Stop the server as described in Quiescing and Stopping Servers.
Uninstall the patch or maintenance pack.
Update the start scripts so that the previous version of WebLogic Server is in the classpath and all environment variables refer to the previous version of WebLogic Server.
Restart the server as described in Restarting Servers.
The new version of WebLogic Server is now uninstalled.
Note the following limitations of rolling upgrade:
Rolling upgrade applies only to upgrades within a major product version. For example, you can upgrade from 10.0 to 10.3.1, but cannot upgrade from 9.0 to 10.0.
When WebLogic Server is installed on a machine and multiple Managed Servers are run from this same installation, you must shut down all Managed Servers that use the same installation before you can upgrade.
During the upgrade process, certain installed files may need to be replaced. However, because the WebLogic Server instance uses these installed files while it is running, the files can be replaced during the upgrade process only after you shutdown the server instance. If multiple managed servers share the same installation of WebLogic Server, all instances that use the set of files must be shut down and upgraded at the same time. In support of rolling upgrade, Oracle recommends that each managed server have its own installation of WebLogic Server.
During the upgrade, you can use new features only after the entire domain has been upgraded.
You should not make configuration changes during the upgrade process until all the servers in the cluster have been upgraded. This is especially true for new configuration options. Servers will silently ignore settings that they do not understand, and the local configuration file may not be updated properly. Also, using new configuration options may prohibit the capability of uninstalling a maintenance upgrade in a rolling fashion.
For a minor release, during the rolling upgrade, there must be two entirely separate installation directories. That is, the location of the old installation and the location of the new installation must be two different directories.