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Trace Files

There are three types of dump files that contain information about errors that occur in the database. Background dumps are written out by Oracle background processes when an error occurs. User dumps are files written for user processes for the purpose of debugging. Core dumps are a place where Oracle dumps core files in a UNIX environment. These may be worth backing up as a history of problems that have occurred to help you troubleshoot future issues. One particular file that should be backed up regularly is a special trace file called an alert log. This file reports on a great deal of activity such as when the database is stopped and started, when checkpoints occurred and the system change number (scn—a unique number given to every change in the database) where the current incarnation or version of the database began. This is all valuable information that can be of great assistance when it comes time to recover your database.

TIP
Back up your alert log with your regular database backups.

You have now seen the structures that are critical to your backup and recovery operations. Armed with this knowledge, you are ready to learn about User-Manager Backup and Recovery.

Progress Check Image

1. Name some files that should be backed up as part of your strategy.

2. What does multiplexing mean and which objects should be multiplexed?

3. Why would you want to use archive logging?

Progress Check Answers

1. Some files that should be backed up include parameter, control, undo, archive log, data, online redo, dump, and trace files.

2. Multiplexing is a term to describe data that's written to more than one location or file at the same time. Redo logs, archive logs, and control files should be multiplexed and each copy should go to a different disk to protect against the loss of one disk.

3. Archive logging allows you to perform full recovery of the database. Without archive logs, no recovery is possible (only restores can be performed). Also, the database can be backed up while it is up and running. It is needed to deliver high availability.

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