Database administration tasks

The database administration tasks relevant to IMS databases are listed in this topic.

Participating in design reviews
Design reviews are a series of formal meetings you attend in which the design and implementation of the database are examined. Design reviews are an ongoing task during the design and implementation of a database system. They are also held when new applications are added to an existing system.
Analyzing data requirements
After the users at your installation identify their data processing requirements, you will construct data structures. These structures show what data will be in your database and how it will be organized. This task precedes the actual design of the database.
Designing your database
After data structures are identified, the next step is to design your database. Database design involves:
  • Choosing how to physically organize your data
  • Deciding which IMS processing options you need to use
  • Making a series of decisions about design that determine how well your database performs and uses available space
Developing a test database
Before the applications that will use your database are cut over to production status, they should be tested. Depending on the form of your existing data, you can use one or more of the IMS Database Design Aids to design, create, load, and test your test database.
Implementing your database design
After your database is designed, implement the design by describing to IMS the database's characteristics and how application programs will use the database.

If your IMS system is enabled to manage application control blocks by using the catalog, you can use the IMS Enterprise Suite Explorer for Development to issue SQL statements that describe the databases and how applications use it.

However, if your IMS system uses an ACB library, this task consists of coding database descriptions (DBDs) and program specification blocks (PSBs), both of which are a series of macro statements. Another part of implementing the database design is determining whether to prebuild application control blocks (ACBs) of the database or to build the ACBs dynamically.

Loading your database
After database characteristics are defined, write an initial load program to put your data into the database. After you load the database, application programs can be run against it.
Monitoring your database
When the database is running, routinely monitor its performance. A variety of tools for monitoring the IMS system are available.
Tuning your database
Tune your database when performance degrades or utilization of external storage is not optimum. Routine monitoring helps you determine when the system needs to be tuned and what type of tuning needs to be done. Like monitoring, the task of tuning the database is ongoing.
Modifying your database
As new applications are developed or the needs of your users change, you might need to make changes to your database. For example, you can change database organization, database hierarchies (or the segments and fields within them), and you can add or delete one or more partitions. Like monitoring and tuning, the task of modifying the database is ongoing.
Recovering your database
Database recovery involves restoring a database to its original condition after it is rendered invalid by some failure. The task of developing recovery procedures and performing recovery is an important one. However, because it is difficult to separate data recovery from system recovery, the task of recovery is treated separately in IMS Version 15.2 Operations and Automation.

You can use Database Recovery Control (DBRC) to support the recovery of your databases. If your databases are registered in the RECON data set, DBRC gains control during execution of these IMS utilities:

  • Database Image Copy
  • Online Database Image Copy
  • Database Image Copy 2
  • Change Accumulation
  • Database Recovery
  • Log Recovery
  • Log Archive
  • DEDB area data set create
  • HD and HISAM Reorganization Unload and Reload
  • HALDB Index/ILDS Rebuild

You must ensure that all database recoveries use the current IMS utilities, rather than those of earlier releases.

Establishing security
You can keep unauthorized persons from accessing the data in your database by using program communication blocks (PCBs). With PCBs, you can control how much of the database a given user can see, and what can be done with that data. In addition, you can take steps to keep non-IMS programs from accessing your database.
Setting up standards and procedures
It is important to set standards and procedures for application and database development. This is especially true in an environment with multiple applications. If you have guidelines and standards, you will save time in application development and avoid problems later on such as inconsistent naming conventions or programming standards.