IBM 000-8697 User Manual

How to Improve Performance

The first step in tuning is to determine the cause of frequent checkpoints. Are
the checkpoints occurring because the physical log is becoming full too
rapidly or as a result of some other event?

To answer this question, examine the value of the

Numpage

 field in the

physical log portion of the

DB-M

onitor Status menu, Logs option, or in the

(lowercase -L) output. The physical log

Numpage

value is the number

of physical log pages used since the last checkpoint. If the value of

Numpage

is close to 75 percent of the physical log size at the time that the checkpoint
begins, the checkpoint was probably initiated as a result of physical log
activity.

If this is the case, you can reduce the frequency of the checkpoint by
increasing the size of the physical log or increasing the specified value of

CKPTINTVL

, the default checkpoint interval. If you wish to increase the

frequency of checkpoints, you can either reduce the size of the physical log
or reduce the specified value of

CKPTINTVL

, the default checkpoint interval.

(Refer to

 for more details about how to increase the size of the

physical log. Refer to

 for more details about how to change the

value of

CKPTINTVL

.)