8.2.2.3 Configuration Practices for Optimal Software Maintenance

When configuring an Exadata Database Machine, it is important to adopt features that will lessen the impact and risk of performing software updates.

Configuration Practice	Use for Software Maintenance	Purpose
Oracle ASM high redundancy disk groups	Rolling updates - Exadata storage servers	When performing storage server updates in a rolling manner with the databases remaining online, it is highly recommended to configure Oracle ASM disk groups with high redundancy. High redundancy disk groups can tolerate the failure of a disk in another storage server during rolling updates. During rolling, or online, storage server updates, the disks for the storage server being updated are taken offline on one storage server by patchmgr while it is updated. After the update completes the disks are resynchronized by Oracle ASM, and then patchmgr starts to update the next storage server. While disks are offline the disk group has reduced redundancy. A normal redundancy disk group with reduced redundancy during a rolling update may dismount and have data loss if a disk fails in another storage server. Oracle ASM disk group redundancy is typically set during initial system configuration. Therefore, consider how you plan to perform storage server updates, rolling or non-rolling, prior to system configuration. An Oracle Data Guard physical standby system can also provide protection against disk failure during rolling storage server update.
Oracle RAC features for client high availability	Rolling updates - Exadata database servers, Oracle Grid Infrastructure or Oracle Database software	When performing Exadata database server, Oracle Grid Infrastructure, or Oracle Database software updates in a rolling manner on one database server at a time while database services remain running on the other servers in the cluster, the database services must be stopped on the Exadata database server being updated. To minimize the impact to client applications connected to database instances that will be stopped during maintenance, configure client applications to use database services, Fast Application Notification (FAN), Fast Connection Failover (FCF), and Application Continuity.
Oracle Data Guard physical standby database	Any rolling or non-rolling update (except Oracle Database patch set and release updates)	Oracle Data Guard Standby-First Patch Apply provides support for different Exadata infrastructure, Oracle Grid Infrastructure, and Oracle Database software between a primary database and its physical standby database for the purpose of applying and validating Oracle patches in rolling fashion with minimal risk to the primary database.
Oracle Data Guard transient logical standby database	Any rolling or non-rolling update	Use Oracle Data Guard logical standby database to reduce database upgrade downtime for patch set and release updates. Database upgrade downtime is reduced by allowing the logical standby database to be upgraded to the new version and kept synchronized while the primary database remains online running the current version.
Oracle GoldenGate	Any rolling or non-rolling update	Use Oracle GoldenGate to reduce database upgrade downtime for patch set and release updates. Downtime during a database upgrade is reduced by allowing the target database to be upgraded to the new version and kept synchronized while the source database remains online running the current version.