IBM DB2 Recovery Expert for Multiplatforms V2 Usage Guide

Chapter 3. Installing and configuring DB2 Recovery Expert 21

3.2.1 DB2 configuration requirements

For a database to be fully recoverable via DB2 RE, the database must be

enabled for log archiving. The following information about how to set the logging

and performance parameters is copied directly from the IBM DB2 Recovery

Expert for Multiplatforms: User’s Guide:

These are the required settings in the DB2 database configuration

parameters that ensure that Recovery Expert functions properly. If Recovery

Expert is used to recover data from one database into another, the

parameters must be set for both databases. In a DB2 multiple partition

environment, you must apply these required settings to all partitions of the

database. Refer to the IBM DB2 UDB Data Recovery and High Availability

Guide and Reference, V8.2 SC09-4831 for more information about how to set

these parameters.

Types of log files

There are different types of DB2 logging. Each type provides a different level of

recovery capability. DB2 RE requires archive logging so that the log files are

retained and can be analyzed to determine possible recovery options.

DB2 versions prior to DB2 UDB V8.2

For DB2 versions prior to DB2 UDB V8.2, archive logging is enabled for a

database by turning on either the LOGRETAIN or USEREXIT configuration

parameters, as follows:

򐂰 Setting LOGRETAIN to YES, ON, or RECOVERY causes DB2 to save archive log files

in the directory that is specified by the database configuration

newlogpath/path.

As active logs fill, DB2 rolls filled logs into archive log files. These archive log

files are used by DB2 RE during recovery analysis or log analysis. You should

save the archived log files until they become obsolete, which typically occurs

after a number of full backups have been done.

Note: If you are installing DB2 Recovery Expert V2 over an existing version of

DB2 Recovery Expert, there are special steps to take and considerations to

examine. These steps are documented in IBM DB2 Recovery Expert for

Multiplatforms: User’s Guide, SC18-956, which is available at:

http://www.ibm.com/software/data/db2imstools/db2tools-library.html

For this book, we start with DB2 Recovery Expert V2. Thus, we do not execute

the special steps.

22 IBM DB2 Recovery Expert for Multiplatforms V2 Usage Guide

򐂰 Setting USEREXIT to YES causes DB2 to perform logging regardless of the

LOGRETAIN setting. Setting the USEREXIT also indicates that a user exit

program must be used to archive and retrieve log files. You must also ensure

that the DB2 RE minilogs are updated before the user exit removes the logs

from availability.

DB2 versions of DB2 UDB V8.2 or higher

In DB2 UDB V8.2 and higher, archive logging is enabled using the LOGARCHMETH1

configuration parameter. LOGARCHMETH1 accepts the following parameters:

OFF This setting is not recommended because log archiving

will not take place.

LOGRETAIN Equivalent to the LOGRETAIN setting.

USEREXIT Equivalent to the USEREXIT setting.

DISK Writes the archive log to disk. This parameter must be

followed by a colon (:) and then a fully qualified existing

path name where the log files will be archived. For

example, DISK:/u/dbuser/archived_logs.

TSM This parameter indicates that log files should be archived

on the local Tivoli Server Management server using the

default management class. If followed by a colon (:) and a

Tivoli Server Management management class, the log

files are archived using the specified management class.

VENDOR This parameter specifies that a vendor library is used to

archive the log files. This parameter must be followed by

a colon (:) and the name of the library. The APIs that are

provided in the library must use the backup and restore

APIs for vendor products.

Performance

The Application heap size (APPLHEAPSZ) database configuration parameter must

be set to at least 128 to provide sufficient memory page space when DB2 RE is

running.