Challenges in backing up large databases
What are the challenges that we should be ready to address when devising a backup and recovery strategy for large databases, typically 10 TB or larger in size? What is the best way to overcome these challenges?
If your database is 10TB in size, then I would recommend using Oracle's Recovery Manager (RMAN) to back up your database. RMAN has many features that help you back up large databases. RMAN supports incremental backups. This way, you only back up changes that have occurred since a previous backup. This can be quite a timesaver. In Oracle 10g, RMAN performs the new Incrementally Updated Backups, which is an incremental backup since the last incremental backup, but also modifies the old backup to have these changes. With the Incrementally Updated Backup, you do not have to restore a base backup and multiple incremental backups, as the Incrementally Updated Backup is the base plus the increments!
Another timesaver with RMAN is to skip READ ONLY tablespaces. It is rare for a 10TB+ database to update many of those terabytes of data on a regular basis. Place the data that is not getting updated in tablespaces separate from the data that does get updated. Then, make the non-updated tablespace READ ONLY. Back it up with RMAN. Since the tablespace is READ ONLY, you do not need to back it up again. You can have RMAN perform a full backup of your database, but skip the READ ONLY tablespaces. You may find that you only need to back up 1TB on a regular basis and your other 9TB were last backed up nine months ago!
Using RMAN is vital to backing up a VLDB. I would suggest going to http://tahiti.oracle.com and reading the backup and recovery guides for your version.
This was first published in September 2006