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IMS 15 Managed ACB Enhancement: OPTION(NOCHECK) to IMPORT DEFN SOURCE(CATALOG)

By Michelle Carey posted Wed March 02, 2022 07:25 PM

  
Take more control of importing your IMS database resources—no more waiting for directory scans to validate associated PSBs! 


For IMS 15 and later, we added a new NOCHECK option, delivered in APAR PH09142/PTF UI64750 an enhancement to the IMPORT DEFN SOURCE(CATALOG) command that improves usability and performance for online dynamic resource changes.

Let's take a closer look.

Added support for importing database resources: support for BLDPSB=NO

We've added a new OPTION(NOCHECK) option to import database resources that were created by using the DFS3UACB utility with the BLDPSB=NO parameter or data definition language (DDL) function that does not include their associated PSB members for the changed databases in the staging directory.

Without this APAR

Before this APAR was available, you use the DFS3UACB utility to create your changed database resources with the BLDPSB=NO parameter and the associated PSBs for the changed database resources are not included in the staging directory.

When you try to dynamically import these changed database resources in the staging directory to online IMS systems, the IMPORT DEFN SOURCE(CATALOG) command fails because it does not find any associated PSB resources for the changed databases. Even though you specify the BLDPSB=NO parameter so as not to include any associated PSB resources to be created in the staging directory, you cannot successfully import these changed database resources.

With this APAR

Now with this new IMS 15 enhancement (PH09142),  you can specify OPTION(NOCHECK) with any existing options in the IMPORT DEFN SOURCE(CATALOG) command to import databases in the staging directory that were created by using the DFS3UACB utility with the BLDPSB=NO parameter or by using DDL. The IMPORT DEFN command will import these changed database resources without their associated PSBs included in the staging directory.

To quickly identify a database resource that is imported without its associated PSB resources, a new diagnostic local status, LclStat, of NO-ASSOCIATED-PSB-FOUND-IN-STAGE is included for any changed database resource imported without its associated PSBs found in the staging directory in the command response. 

New helpful status messages

We've added new messages, DFS4896I and DFS4897I, or DFS4896I and DFS4898E to the IMS type-2 IMPORT DEFN SOURCE(CATALOG) command to show success or failure of the IMPORT DEFN online change.

Without this APAR

The IMPORT DEFN SOURCE(CATALOG) command does not have any messages in IMS job logs to show an IMPORT DEFN SOURCE(CATALOG) online change has occurred.

Some users have suggested that it would be helpful to have the IMPORT DEFN online change messages shown in IMS job logs similar to the library-switch ACBLIB online change. For diagnostic purposes, you can easily review the IMS job logs to see whether any online changes occurred.

With this APAR

We listened to your suggestions and added three new event messages for IMPORT DEFN SOURCE(CATALOG) command in the IMS job logs for each sharing IMS system that participates in an IMPORT DEFN online change:

DFS4896I IMPORT DEFN SOURCE(CATALOG) PROCESSED ONE OR MORE RESOURCES, COMMAND TOKEN=command_token

  • DFS4896I is issued if there is no “Prepare Phase Error”.

DFS4897I IMPORT DEFN SOURCE(CATALOG) COMPLETED, COMMAND TOKEN=command_token

  • DFS4897I is issued if DFS4896I is issued, and the command is successful.

DFS4898E IMPORT DEFN SOURCE(CATALOG) FAILED, COMMAND TOKEN=command_token

  • DFS4898E is issued if DFS4896I is issued, and the command fails.

You can use the command_token to print the associated X’70’ log records for the IMPORT DEFN SOURCE(CATALOG) command. 

Improved performance

Finally, we improved performance.  The new OPTION(NOCHECK) adds support to import database resources to bypass the directory scan validation for associated PSBs that are required to be rebuilt for the changed databases. 

The catalog directory scan process can be time consuming when the catalog directory contains a large number of members. If the changed database resources are created correctly in the staging directory using the DFS3UACB utility, the IMPORT directory scan validation is redundant.

Without this APAR

The IMPORT DEFN SOURCE(CATALOG) command performs a directory scan to validate that all associated PSBs are included in the staging directory for databases with structural changes. If your directory contains a large number of members, this directory scan can take a long time and will prolong the IMPORT DEFN online change. 

This IMPORT DEFN directory scan validation is redundant if the changed database resources are created correctly in the staging directory by using the DFS3UACB utility.

With this APAR

With IMS 15 and PH09142, you can now specify OPTION(NOCHECK) with any existing options in the IMPORT DEFN SOURCE(CATALOG) command to tell IMS to bypass scanning the directory to find all PSBs that are required to be rebuilt for the changed databases.

If you know that the changed resources are created correctly in the staging directory by using the DFS3UACB utility, specifying OPTION(NOCHECK) in the IMPORT DEFN SOURCE(CATALOG) command improves the IMPORT DEFN performance, especially for directory with a large number of resources because IMPORT DEFN with option NOCHECK bypasses the directory scan. 

The performance improvement can be huge depending on the number of members in the directory.

Although OPTION(NOCHECK) must be explicitly specified, you can disable its use in case it is mistakenly specified. If you want to disable OPTION(NOCHECK) for your organization, you can use the OM Input Exit to reject the IMPORT DEFN SOURCE(CATLAOG) OPTION(NOCHECK) command.

Find more information on this enhancement in the IMS documentation.

So, take that control!

With the new OPTION(NOCHECK), we hope you find the IMPORT DEFN SOURCE(CATALOG) support of BLDPSB=NO, new event messages in IMS job logs for IMPORT DEFN SOURCE(CATALOG), and performance improvements helpful in easing your migration to and adoption of managed ACBs. 


Originally published October 10, 2019 and updated on October 15, 2019 by IMS Development

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