For most companies Oracle database applications are critical to everyday business functions, therefore, regular, successful backup of Oracle data is a necessity. But not all Oracle installations are the same. The type of Oracle data, the frequency of data changes, and your approach to database management should all play a key role in how you implement Oracle backup procedures. This TechTip describes best practices in choosing and deploying Oracle database backup scenarios for a variety of data types and DBA strategies using Veritas NetBackup.
Oracle’s built-in backup utility, Recovery Manager (RMAN), can be used for basic database backups, but it lacks support for storage devices such as tape and tape libraries. Most administrators will opt for this method when cloning a database for use on another host or when migrating a database to another operating system. Also, since RMAN is a disk-based backup only, you must have sufficient storage allocated for full and incremental backups. This may be the best solution in small database environments, or in companies that rely on database administrators to perform most or all of the Oracle maintenance and protection. For these reasons, RMAN alone may not be the best solution for Oracle backup in your environment.
Using NetBackup with RMAN
The NetBackup Oracle Agent can be used in conjunction with RMAN to perform a more advanced set of protection options. In this scenario, RMAN puts the database in hot backup mode, and data is sent from the Oracle DB to a NetBackup Master or Media server. A GUI-based Oracle RMAN script wizard allows you to select the data, the type of backup to be performed, the backup schedule, RMAN I/O values, and backup set limits. A similar wizard is used to generate RMAN Recovery and Restore scripts. The restore wizard provides a browser-based interface for selecting SID (system ID), granularity, and objects for recovery. There are some drawbacks to this method, however. Since data is streamed from the database in hot backup mode, performance of the database may slow the production Oracle server considerably. When not using the RMAN Recovery Catalog, NetBackup needs to make additional copies for recovery use.
NetBackup Snapshot Client and Oracle
Snapshots can be used to capture a DB state at a particular time as input for the backup process. Using NetBackup Snapshot Client, RMAN and NetBackup put the database in a consistent state, and then NetBackup initiates a snapshot of the data through the Media server. Using this technique you can easily perform an off-host backup, moving the data onto an alternate client or media server so that backups are performed without impacting the Oracle production server. This technique is best used in environments where many Oracle backups or snapshots are required and where optimum performance of the Oracle production server is required. This technique also provides a smaller backup window and improved availability of data as the DB is not in hot backup mode. One disadvantage is that this scenario requires a snapshot hardware and/or software provider to support the NetBackup Snapshot Client.
Oracle CDP with NetBackup RealTime Protection
Continuous Data Protection (CDP) allows Oracle administrators to continuously capture every disk write change from the database to a secondary disk. CDP gives you the ability to ‘roll-back’ the database to any point in time through the NetBackup console. Since only changed blocks are sent for backup, RealTime Protection will have minimal impact on the production server, will give you the finest granularity in selecting restores, and allows Oracle DBAs to quickly roll back to a previous time-frame in the event of a database crash or corruption. RealTime Protection does not integrate with the Oracle recovery agent console, however, and all restores must be made through NetBackup. Also, RealTime requires a kernel driver on the application host that may impact performance slightly (typically five percent).
Depending on your Oracle application size, complexity, and protection criteria, NetBackup and NetBackup agents can provide many options for database backup and recovery. Used in combination, they are even more powerful and flexible.