DB2 UDB V8.2 on the Windows Environment

Chapter 3. Administration and management 67

If you use a user-provided compression library, the library is stored in the backup

image by default and will be used on restore. The command syntaxes are:

DB2 BACKUP DATBASE sample COMPRESS COMPRLIB libname COMPROPTS options

DB2 RESTORE DATABASE sample COMPRLIB libname COMPROPTS options

In these examples, COMPROPTS is used to pass the options to the compression

library.

Use of the automatic database function could create some CPU costs due to the

compression computation. However, the media I/O time will be decreased

because the image size is smaller. The overall backup/restore performance

impact depends on whether CPU or media I/O is a bottleneck of the system.

3.1.4 Logs in backup images

DB2 transaction log files are essential for restoring and recovering a database or

table space to a consistent point in time using online backup images. Prior to

Version 8.2, the backup and restore utilities required shipping the backup image

and corresponding log files as separate objects to the disaster recovery sites.

This risks losing the log files required for recovery. The new enhancement

enables you to include the logs on the online backup. This way, you can ship the

backup images with the log files to ensure that the backup will be restorable if

archived logs are misplaced. This feature supports all types of online backups

such as database, table space, incremental, and compressed.

If the INCLUDE LOGS option is specified in the backup command, DB2 will

truncate the tail log file and close it after the table space or database is backed

up. All logs that are needed to restore the backup and roll forward to the time

corresponding to the end of the backup are placed in the backup image. DB2

backs up log files in parallel with backing up the table space data. If database

backup compress is specified, the log files will be compressed as well.

By default, the log will not be backed up with the database or table space backup

image. To use this feature, specify the INCLUDE LOGS option in the backup

command, such as:

DB2 BACKUP DB sample ONLINE TO d:\db2backup INCLUDE LOGS

When restoring the database, specify the directory where you want DB2 to place

the log files. For example:

RESTORE DB sample ONLINE FROM d:\db2bckup LOGTARGET d:\db2logs

ROLLFORWARD DB sample TO END OF LOGS AND STOP OVERFLOW LOG PATH d:\db2logs

You also can restore log files only from the integrated backup image:

RESTORE DB sample LOGS FROM d:\db2backup LOGTARGET d:\db2logs