You can make a copy of your database by taking a user archive using Data Restore. This copy can be on tape or DASD.
You can take the backup on either of 2 different device types (tape and tape, tape and disk, or disk and disk) at the same time, so that, for example, one copy can be taken offsite for archiving while the other copy is kept onsite for recovery purposes.
The file that is produced contains a copy of the directory and all dbextents that contain data if processing a BACKUP or BACKUP FULL function.
A new option can be used to produce a file that contains the directory and all dbextents pages modified since the last BACKUP FULL function. This function is the BACKUP INCREMENTAL and can save a lot of time to shorten the duration of application server shutdown.
| Note: | To ensure database integrity, you can only take a user archive when you have stopped the application server. |
To execute the recovery process to apply all changes referenced in the log files, the database has to run in LOGMODE=A or LOGMODE=L. This will allow point-in-time recovery to be performed.
You should take a backup of each database regularly, so that if a system failure occurs and restoration is required, the time to restart the server is minimized.
For example, suppose you have taken a database backup every Friday evening, and a log archive on Tuesday and Thursday evenings, and on the next Friday, a media failure occurs. You would have to restore the last backup and reapply all changes processed on the database during the whole week using the log archives. If there was heavy activity that week, this process can take a long time.
If the backup is processed every day, and a media failure occurs, after restoring the database, only the changes made to the database on that day will have to be reapplied. Consequently, the server will be down for a shorter period of time.
| Note: | You must balance the time and resources required to perform the database archives against the risk of failure and the acceptable time for recovery. |
You can take a database archive using either the DB2 Server for VSE & VM database archive or the Data Restore backup facility.
You can back up only the parts of the database which have been modified since the last full backup using the INCREMENTAL BACKUP function.
For example, support a full backup is executed on Sunday night, and an incremental backup is taken each day. The incremental backup produced on Monday will only contain pages that were modified on Monday. The incremental backup taken on Tuesday, will contain all pages that were modified on Monday and Tuesday (all pages modified since the last FULL BACKUP function). When a RELOAD is done using the incremental archive taken on Tuesday, the RELOAD process requires the Tuesday incremental archive tape and the associated full archive taken on Sunday. The incremental tape from Monday is not required.