Acquire the following tuning information:

1. Information about CPU and disk I/O operations
2. Statistical information about the global buffer
3. Statistical information about the deferred write processing

To acquire 1, use the appropriate OS function. To acquire 2 and 3, use the statistics analysis utility.

Check the statistical information about the deferred write processing whose cause (CAUSE) is S (synchronization point processing). If one of the following conditions is satisfied, proceed to (3). If neither of the conditions is satisfied, proceed to (9).

• When the facility for parallel writes in deferred write processing is not used
  Total WRITE time (DWSUM, DWSUMM) > synchronization point acquisition interval (time)
  
• When the facility for parallel writes in deferred write processing is used
  Parallel WRITE time (DWPARA, DWPARAM) > synchronization point acquisition interval (time)
  

Obtain the synchronization point acquisition interval from the difference between the output times of the following messages:

• KFPS02183-I (message displayed when synchronization point processing is completed)
• KFPS02179-I (message displayed when synchronization point processing is skipped)

If the average WRITE unit time for the statistical information about deferred write processing (DWAVG and DWAVGM) is extremely poor compared to the disk write performance, do the following (if these do not apply, proceed to (4)):

• Check for a disk failure.
• Because a problem such as disk contention might have occurred, use OS functions to acquire tuning information about input/output operations, and perform tuning based on the results. If there is no leeway for tuning, proceed to (4).

If synchronization point processing is skipped, the KFPS02179-I message is displayed. If any of the utilities listed below was executing during the period in which this message was displayed, consider changing the operating method (if this does not apply, proceed to (5)):

• When the database load utility, database reorganization utility, or rebalancing utility is executing
  Use the local buffer by specifying the -n option for the utility's execution. If the local buffer cannot be used, proceed to (5).
  
• When the free page release utility is executing
  Specify the -p option for the utility's execution. If the -p option cannot be specified, proceed to (5).
  

Evaluate whether the synchronization point acquisition interval can be made longer. If it cannot be made longer, proceed to (6). You use the pd_log_sdinterval operand to change the synchronization point acquisition interval.

Perform the tuning described in 23.3.3(1) Reducing the deferred write trigger interval and in 23.3.3(2) Increasing the update page output rate during deferred write trigger. If the problem is not resolved after tuning, proceed to (7).

If there is enough room in the CPU, perform the tuning described below. If there is not enough room in the CPU, proceed to (8).

• When the facility for parallel writes in deferred write processing is not used
  Specify the pd_dfw_awt_process operand to use the facility for parallel writes in deferred write processing. If this does not resolve the problem, proceed to (8).
  
• When the facility for parallel writes in deferred write processing is used
  Perform the tuning explained in 23.3.3(3) Increasing the number of parallel write processes in deferred write processing. If tuning does not resolve the problem, proceed to (8).
  

Specify the pd_dfw_syncpoint_skip_limit operand to limit the number of update buffers. In this case, note that when the skip count for synchronization point processing reaches the maximum value, the performance of an update transaction decreases because the update buffer is output at the extension of the update transaction.

If the pd_dfw_syncpoint_skip_limit operand cannot be specified, evaluate a disk enhancement.

If any of the following events has occurred, tune the global buffer:

• Buffer lock-release wait (WAITL) occurs frequently.
• Output wait (WAITW) occurs frequently.
• The lock-release contention rate (SLEPR) in global buffer lock processing is high.
• The update buffer flushes count (UPFLS) has increased.

For details about the above information and the tuning of the global buffer, see 23.1 Tuning global buffer pools.