Performance tips for the Smart Reorg utility

Use the following techniques to improve the performance of Smart Reorg utility jobs.

Tip: Many of the control statements and their values introduced in this topic can be set in the Installation Default Option Table (HPSCOPTI) so that the control statement values are always applied.

To learn more about the Installation Default Option Table, see Setting installation default options.
For a JCL example to set these values in HPSCOPTI, see Example: Changing default values to achieve best performance (Smart Reorg, IPR Unload, IPR Reload).

If you used the IMS Tools Setup to customize your tools, you can refer to the generated customization JCL for your specific environment in your.hlq.CUSTJCL(#A6GBLRX).

High Performance I/O Driver

You can reduce the elapsed time and the CPU usage by using the High Performance I/O Driver in the Reload task and the image copy task.

If all the libraries that are concatenated in the STEPLIB are APF-authorized, the HPIO option (HPIO=YES) is enabled automatically and the High Performance I/O Driver is used during the job.

If the library for IMS DFSMDA members is not APF-authorized, you can add the IMSDALIB DD statement to specify the library.

For more information, see HPIO control statement.

You can set this value in the Installation Default Option Table (HPSCOPTI) so that the value is always applied. Use the following example to specify this value in HPSCOPTI:

HPSCOPT DRIVER,HPIO=YES

zIIP processor

A portion of VSAM ESDS I/O or OSAM LDS I/O workloads can be offloaded to IBM® System z® Integrated Information Processor (zIIP) and reduce the use of the main CPU.

To enable zIIP processing, specify the ZIIPMODE=COND control statement in the (REORG) block of the HPSIN DD statement. Certain conditions must be satisfied to enable zIIP processing. For more information, see ZIIPMODE control statement.

You can set this value in the Installation Default Option Table (HPSCOPTI) so that the value is always applied. Use the following example to specify this value in HPSCOPTI:

HPSCOPT DRIVER,ZIIPMODE=COND

High performance data transfer service (IPRPIPE)

IPRPIPE provides a high performance data transfer service between reorganization tasks. In order to avoid timeouts while establishing connection between each task, consider specifying the PIPEWAIT option in the Installation Default Option Table (HPSCOPI).

Use the following example to specify this option in the HPSCOPTI:

HPSCOPT DRIVER,PIPEWAIT=15

For more information, see PIPEWAIT control statement.

Suppress printing of statistics reports

You can suppress printing of some statistics reports to reduce CPU usage and improve the performance.

To suppress printing of some reports, specify the STATUL=NO and the STATRL=NO control statements in the (REORG) block of the HPSIN DD statement. For the type of reports that are suppressed, see STATUL control statement and STATRL control statement.

You can set the STATRL value in the Installation Default Option Table (HPSCOPTI) so that the value is always applied. Use the following example to specify this option in the HPSCOPTI:

HPSCOPT DRIVER,STATRL=NO

Exclude the ILDS build process

This tip applies to HALDB that has no logical relationships defined.

If you specify the PSINDEXBLD control statement so that all the PSINDEXes are built in the Smart Reorg job, or if you are planning to build all PSINDEXes by using IMS Index Builder after the Smart Reorg job, the Indirect List data sets (ILDSs) do not need to be built in the Smart Reorg job.

Specify the ILDSBLD control statement in the (REORG) block of the HPSIN DD statement or set this value in the Installation Default Option Table (HPSCOPTI) to control the behavior of the ILDS build process.

ILDSBLD=YES,INITONLY specifies to initialize the ILDSs without creating ILEs (indirect list entries) and, thus, reduces the use of the CPU and the shadow space.
ILDSBLD=YES,COND specifies that the Smart Reorg job applies the ILDSBLD=YES,INITONLY option only when the HALDB has no logical relationships and all PSINDEXes are to be built by specifying the PSINDEXBLD control statement or by using WFP data sets.

For more information, see ILDSBLD control statement.

To set this value in the Installation Default Option Table (HPSCOPTI) so that the value is always applied, use the following example:

HPSCOPT DRIVER,ILDSBLD=(YES,COND)

CAB sequential I/O for OSAM data sets

To improve the performance of CAB sequential I/O for OSAM database data sets, consider specifying the CABBASE_OS option in the Installation Default Option Table (HPSCOPTI). Use the following example to specify this value in HPSCOPTI:

HPSCOPT DRIVUL,CABBASE_OS=8

If you do not want this value in the HPSCOPTI, you can specify it in the (UNLOAD) block of the HPSIN DD statement as follows:

CABBASE=8,OSAM,SEQ

For more information, see CABBASE control statement.

Compressed segment data

The DECOMPRESS control statement specifies to call the segment compression routine to decompress all segment types that have COMPRTN specified on their related SEGM statements in the DBD. DECOMPRESS=NO, which is the default, reduces the use of CPU during unload and reload processing because it specifies not to expand segment data that was compressed by a Segment Edit/Compression exit routine.

Specify DECOMPRESS=YES in the (UNLOAD) block of the HPSIN DD statement only if a user exit routine is specified or the Segment Edit/Compression exit routine was changed.

For more information, see DECOMPRESS control statement.

I/O performance for (P)HDAM that has many overflow segments

If your HDAM or PHDAM database has many overflow segments and the Smart Reorg utility job uses the High Performance I/O Driver (HPIO option), you can improve the I/O performance further by enabling the OADSPR option. OADSPR=YES specifies to reduce the usage of data space that is required when processing the overflow area.

Note: OADSPR=YES is applicable only to HDAM and PHDAM databases. The Smart Reorg utility ignores OADSPR=YES if the database organization is not HDAM or PHDAM.

To enable the OADSPR option, specify OADSPR=YES in the (RELOAD) block of the HPSIN DD statement. For more information, see OADSPR control statement.

You can also set this value in the Installation Default Option Table (HPSCOPTI) so that the value is always applied. Use the following example to specify this value in HPSCOPTI:

HPSCOPT DRIVRL,OADSPR=YES

Avoid unnecessary sort processing in Reload task

Physical sequential sort processing occurs before reload. You can avoid unnecessary sort processing to reduce elapsed time.

To avoid unnecessary sort processing, specify the SORT=COND control statement in the (RELOAD) block of the HPSIN DD statement. If REORGINPUT=ULDS is specified, the following conditions must be satisfied to enable SORT=COND:

The input unloaded data set must be created by the IPR Unload utility or IMS HP Unload with the CHECKREC=YES option.
The format of the unloaded data set must be in HD format or in short header format.

For more information, see SORT control statement.

You can also set this value in the Installation Default Option Table (HPSCOPTI) so that the value is always applied. Use the following example to specify this value in HPSCOPTI:

HPSCOPT DRIVRL,SORT=COND

Tip to improve Type-A image copy processing

If the database is either HISAM or SHISAM, specify a value greater than 1000 for the DBBUF parameter of the GLOBAL statement in the ICEIN DD.

With Type-A image copy, the DBBUF parameter defines the number of queuing buffers between the reload process and the image copy process, and the default value is 250. Generally the CI size of a HISAM or SHISAM database is small. In such a case, the buffers are used up frequently causing the reload process to suspend until all the data in the buffers is processed by the image copy process. Specifying more than 1000 for the DBBUF parameter increases the number of buffers and prevents performance deterioration.

Tip to improve Type-B image copy processing

Image Copy processing for database data sets runs in parallel unless IC control statements for database data sets are specified in ICEIN DD. The maximum number of parallel tasks is defined by the TASKCTL parameter and the default is 15. If errors occur due to insufficient storage, specify a value less than 15 for the TASKCTL parameter of the GLOBAL statement in the ICEIN DD to reduce the number of parallel tasks.

Note: If APAR PI71145 is not applied to IMS High Performance Image Copy 4.2, the default value for the TASKCTL parameter is 253.

Examples for modifying HPSCOPTI

You can refer to examples in HPSCOPT macro statement examples to modify the Installation Default Option Table (HPSCOPTI).