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Recovering OracleAS Instance after Node Failure February 11, 2008

Posted by Manpreet Johal in Oracle Application Server.
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In earlier post, we discussed about OracleAS Recovery Manager, a tool to perform backup and recovery operations at Oracle Application Server instances. In this post we will discuss about Loss of Host Automation (LOHA), a feature of OracleAS Recovery Manager to recover OracleAS node after operating system or hardware failure.

LOHA provides a solution for a loss of host when you want to restore the original instances to a new environment without having to reinstall the instances and preserve the application data. LOHA automates the tasks necessary for the Oracle Application Server administrator to migrate Oracle Application Server instances from one host to another. The new host can be a different host running the same operating system or the same host after system re-install.

Following are the few points to be considered while using LOHA:

  • LOHA supports all middle-tier installations (Web Cache, J2EE, Portal/Wireless, Business Intelligence and Forms), and the new host’s name can be the same or different from the original host.
  • For metadata repositories and Infrastructure installations, only the target host name must be the same as the original host.
  • For an Oracle Identity Management installation, full automation is supported if the new hostname is the same as the original.
  • LOHA does not support the Toplink standalone install type.
  • Manual work is required for different host names.

LOHA can move all the Oracle Application Server instances from one host to a new host if the new host does not have any other Oracle Application Server instances already running.

Like OracleAS Recovery Manager, Loss of Host Automation (LOHA) is a functionality that must be utilized by OracleAS deployments.

How LOHA recovers the OracleAS instance to new host?

It make use of node/image backup performed at former host to build the environment at target host.

In order to implement LOHA, one can refer to standard OracleAS 10g R2 documentation.

References:

What is OracleAS Recovery Manager? January 6, 2008

Posted by Manpreet Johal in Oracle Application Server.
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In this article, I am putting some glimpse on OracleAS Recovery Manager (earlier known as OracleAS Backup and Restore Tool), which is a perl based tool to perform backup and recovery operations for Oracle Application Server 10g installations i.e. Infrastructure and Middle-Tiers.  It is installed by default when OracleAS 10g Middle-Tier or Infrastructure is installed.

I have seen customers who have implemented Oracle Application Server instances and are relying on daily cold backup strategy for Infrastructure and Middle-Tier instances. Very few are using Oracle Database Recovery Manager (RMAN) to backup Metadata Repository Database.

OracleAS Recovery Manager is a tool that supports online backup for configuration files (including the J2EE applications deployed) and Metadata Repository Databases. It supports two types of backups for Oracle Application Server:

1. Image Backup: It includes the Oracle home directory for that instance, the OraInventory directory, the oratab file, and Windows registries on that node and finally a cold instance backup of that Oracle Application Server instance. Following images shows the files that are backed up during Image Backup:

2. Instance Backup: It includes the configuration information of Oracle Application Server components and deployed applications.  Instance backup is further divided into three types:

i) OracleAS Infrastructure Backup: It backs up the entire Oracle Metadata Repository database. Next, the tool requests Distributed Configuration Management (DCM) to create and export a consistent archive (jar file) of the configuration schemas from the DCM repository for DCM-managed components like Oracle HTTP Server (OHS) and OracleAS Containers for J2EE (OC4J). Then, the tool adds the archive file to the backup.

ii) OracleAS Middle-Tier Backup: It backups the configuration information of all its Oracle Application Server components and deployed applications. Some of these components, like Portal, Wireless, Integration B2B, and Oracle Business Intelligence Discoverer are not managed by DCM. They have their product metadata in the Oracle Application Server Metadata Repository database which is backed up by the Backup and Recovery Tool in the Oracle Application Server Infrastructure instance.

However, it can also be used to perform backup and recovery operations for Metadata Repository Databases created using Metadata Repository Configuration Assistant (MRCA).

As a best practice, Image Backup should be performed after installation or whenever any major configuration change (e.g. patch application) is performed. It serves as a baseline backup for all subsequent Instance Backups. Instance backup should be performed on regular basis.

OracleAS Recovery Manager provides another powerful feature known as Loss of Host Automation (LOHA). LOHA automates the tasks necessary for the Oracle Application Server user to migrate Oracle Application Server instances from one host to another. E.g. if you lost the operating environment due to hardware failure and you need to setup the complete environment at new machine, with fresh operating system; LOHA provides the functionality to restore the OracleAS instance to new machine by setting Oracle installation environment i.e. registry entries (for Windows), oratab entries (for UNIX/Linux), oraInventory entries, and system files. LOHA utilizes Image Backup to restore the OracleAS instance to its backed up state. I will explain more about this feature in future posts.

This tool is pretty simple to configure. Administrators can configure it via command line or using OracleAS Control Console. After configuration it populates backup template scripts located at ORACLE_HOME/backup_restore directory as per environment and components installed.

OracleAS Recovery Manager uses RMAN for database backups and recovery. It supports full and incremental backups for configuration files and databases. Administrators can use the pre-defined incremental backup scripts with various levels (Level 0, Level 1, Level 2, Level 3, and Level 4) and can customize them as per backup strategy requirements. Incremental backup levels are applicable to database backups only, and are not applicable for configuration files. So if administrator is using incremental scripts specifying Level 1, it will perform Level 1 incremental backup for Metadata Repository database and standard incremental backup for configuration files.

Moreover, this is the tool which provides underlying functionality in OracleAS Disaster Recovery configuration to restore node configuration i.e. OracleAS Guard make use of OracleAS Recovery Manager to read configuration changes at active node and apply at standby node.