Prevent application performance degradation and attain better free space usage

As records in a DEDB area are added, updated, and deleted, free space can be fragmented or segments in a database record can be stored across a large number of separate CIs. Fragmentation of free space and scattered segments can cause the performance of applications to suffer. When available space is used up, new segments cannot be added.

Reorganizing fragmented free space of an area can prevent performance degradation by using free space more efficiently.

Tuning a DEDB area often involves significant and time-consuming database administration tasks including increasing the amount of free space, changing the database structure, or adding and deleting areas. These tasks often require the database or areas to be taken offline, which might not be an acceptable option for some organizations.

IMS Fast Path Solution Pack provides various offline and online reorganization solutions to simplify these reorganization and tuning tasks. You can choose the solution that best meets the needs of your operation environment.

Offline solutions

IMS Fast Path Solution Pack provides a complete set of high-performance utilities to unload, reload, and reorganize DEDB areas of offline IMS Fast Path databases.

IMS Fast Path Advanced Tool provides the following batch offline reorganization solutions:

  • IMS Fast Path Advanced Tool combines the Unload function and the Reload function to provide a high-speed method for reorganizing offline Fast Path databases. The integration of the Unload and the Reload functions processes DEDB areas faster than when the segments are read and inserted by using IMS online applications. This method creates an intermediate file (a sequential file that contains unloaded segment records) that can be used to obtain specific database statistics for data analysis or that can be used to create DEDB areas for testing purposes.
  • The Change function is also a high-speed reorganization function. This function does not create an intermediate file; however, because the segments in DEDB areas are unloaded and reloaded in a single job step, the Change function works faster than using the Unload and the Reload functions together.
  • The Reorg function evaluates units of work (UOWs), which are the smallest unit for reorganization process in DEDB areas, ranks the UOWs, and reorganizes the sets of UOWs based on the ranked set of UOWs. All these processes are done in a single job step. The Reorg function requires less space than other reorganization functions.
  • The Initialize function is a high-speed initialization function. This function initializes multiple DEDB areas efficiently by processing multiple DEDB areas concurrently in a single job step.

Online solutions

The ability to reorganize online DEDB areas is crucial in certain operating environments. For database administrators who must keep their IMS environments online 24 hours a day, 7 days a week, IMS Fast Path Solution Pack provides a set of reorganization utilities to reorganize online DEDB areas. These utilities are designed for optimal online system performance, while retaining a consistent view of IMS data. The reorganization processes are accomplished without taking the DEDB areas offline and without disrupting applications that access the areas; therefore, applications can read and update data in the DEDB areas even while the utilities are running.

The following online reorganization solutions are provided by IMS Fast Path Online Tools:
  • The Online Expert Reorganization utility evaluates UOWs in DEDB areas, ranks the UOWs, and reorganizes a user-specified number of highly ranked UOWs.
  • The Online Area Extender utility dynamically extends the size of the DEDB area. You can specify the portion of the area to extend: the independent overflow (IOVF) portion, the sequential dependent (SDEP) portion of the DEDB area, or both.

These utilities can be run as stand-alone utilities, but if you use the Online Space Management utility, you can run both utility processes (Online Expert Reorganization utility process and Online Area Extender utility process) in one job step.

IMS Fast Path Solution Pack also provides the Online Structure Change utility. You can use the Online Structure Change utility to restructure online DEDB or areas with minimal impact to database availability. The utility supports changing DBD descriptions, randomizing modules, and segment edit/compression routines.

Tuning capability

IMS Fast Path Solution Pack provides a tuning capability that simplifies reorganization tasks even further. The FPA Tune function helps you determine the effective database definitions by evaluating the potential benefits, or impact, of changes to an existing DEDB without the overhead of unloading and reloading the databases. You can use this function to measure the effectiveness of reorganizing fragmented free space or of changing new database definitions without reorganizing the areas. With this function, you do not need to generate new ACBLIBs; database definitions are specified by function keywords, and you can identify the optimal definitions by changing only the function keywords and rerunning the job. By ensuring that your new database definition is effective before reorganizing your database, you can avoid rerunning reorganization jobs that might be caused by inadequate database definitions.

With most of the previously mentioned functions, you can take image copies, validate database pointers, and obtain statistical information reports of the reorganized databases in a single job step. The solutions that are provided in IMS Fast Path Solution Pack help you maintain the health of your databases, improve your productivity, and achieve a smaller maintenance window.