Preparation Is Key to Upgrading IMS the Easy Way
The earth has spun around the sun almost as long as IMS has been around. Yes, it’s an exaggeration, but many shops still use IMS as part of their mission-critical strategy of data storage and delivery. IBM has continually made it viable and relevant in a world of Java and clouds. IMS is here to stay—but you already know that. You also know that this is NOT the problem.
There’s a whole generation of systems programmers that are now or will soon be supporting IMS. And no matter how usable IMS is made, it can be a challenge to upgrade and maintain, whether you’re a consummate systems programmer new to IMS or just new to it in a support role. Consequently, some of its processes differ from any other database management system (DBMS) installation or upgrade. So let’s touch on the terminology and explain some of the “gotchas” of IMS systems programming work.
IMS Version 12 Hits
If you’ve looked at IMS version 12, you probably noticed something new—the IMS repository. It makes it easier to define and manage IMS by storing elements like the physical data set name of the overflow sequential access method (OSAM) or VSAM cluster (MODBLKS), the DDName it’s defined to, and many other database/application artifacts. If you’re already supporting DB2, you will note the faint similarities to the DB2 catalog, which shouldn’t be too surprising if you’ve been following the direction of many DBMS products.
But the repository is new and optional in IMS V12. As a caveat, go into using the repository with eyes wide open. Like many new functions, be mindful of:
- Naming conventions for repository objects: Does it work with the current shop standard naming convention?
- Started tasks and address spaces: Task automation, production UserID and workload manager are a few things to review.
- Usage with existing tasks: Common services layer (CSL) and changes to existing IMS instance(s) should be considered.
- Ancillary but related task set-up: Usage with cross-coupling facility (XCF) services can be key.
- Security and access: Be sure to grant the correct set of rights to read and update the repository for applicable staff and production UserID.
While many new functions are a welcome relief, there are growing pains associated with them. The IMS repository is a strategic direction for IMS, but you may only want to consider this enhancement for your test IMS environment so that you can work with and learn about it. Carve out time after upgrading to IMS V12 to install and use the IMS repository before launching companywide.
Along with the IMS repository, new functional enhancements were added to Database Recovery Control (DBRC). One of these features was improving the time granularity using LIST.HISTORY with TIMELINE. Figure 1 shows an example of the information provided. When faced with a recovery scenario or trying to do root-cause analysis into what transpired during an update, this option is much easier to do than skulking around in the z/OS log or the IMS address space.
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