Performance Tuning for Content Manager

Chapter 8. Tuning DB2 for Content Manager 247

8.6.36 Number of primary log files (LOGPRIMARY)

Impact

DB - Medium

Description

The primary log files establish a fixed amount of storage allocated to the recovery

log files. This parameter enables you to specify the number of primary log files to

be preallocated.

Under circular logging, the primary logs are used repeatedly in sequence. That is,

when a log is full, the next primary log in the sequence is used if it is available. A

log is considered available if all units of work with log records in it have been

committed or rolled-back. If the next primary log in sequence is not available, then

a secondary log is allocated and used. Additional secondary logs are allocated

and used until the next primary log in the sequence becomes available or the limit

imposed by the logsecond parameter is reached. These secondary log files are

dynamically deallocated when the database manager no longer needs them.

The number of primary and secondary log files must be less than or equal to 256.

Default values (range)

3 (2 - 256)

To update

Run the following DB2 command:

db2 update db cfg for <database name> using LOGPRIMARY <parameter

value>

Our recommendation

The Content Manager installation program changes this value to 10 for the

Library Server database, and 25 for the Resource Manager database.

The value chosen for this parameter depends on several factors, including the

type of logging being used, the size of the log files, and the type of processing

environment (for example, length of transactions and frequency of commits).

Increasing this value increases the disk requirements for the logs because the

primary log files are preallocated during the very first connection to the database.

If you find that secondary log files are being allocated frequently, you might be

able to improve system performance by increasing the log file size (LOGFILSIZ)

or by increasing the number of primary log files.