Controlling the overall system impact of a HALDB Online Reorganization

Your options for controlling the impact of an online reorganization on your IMS system include:

• Specifying a separate buffer subpool for the data set being reorganized by using the DBD statement in the DFSVSMxx member in the IMS.PROCLIB data set.
• Adjusting the rate at which the online reorganization runs by using the RATE parameter of the INITIATE OLREORG and UPDATE OLREORG commands.

Specifying a separate buffer subpool for the data set being reorganized can reduce buffer contention between the online reorganization function and other processes that also require buffer resources.

Adjusting the value of the RATE parameter can also help minimize the impact of an online reorganization on the IMS system by introducing an intentional, periodic delay in the online reorganization process, which allows other IMS work to proceed.

You specify the RATE value as a percentage, with values less than 100 representing the addition of the intentionally introduced delay.

The default value for the RATE parameter is 100, which allows the online reorganization to run as fast as possible, depending on system resources, system contention, and log contention, with no intentionally introduced delay. However, if you set the RATE value to 25, for example, IMS adds a delay to the reorganization processing so that 25% of the total processing time for a unit of reorganization is spent copying the data, and the remaining 75% is spent in an intentionally introduced delay. Thus, RATE(25) would cause the online reorganization to take approximately four times as long to run as it would have run with RATE(100).

You can change the RATE value at any time by issuing the UPDATE OLREORG command.