Reorganization function overview

In many cases, the need to reorganize an area does not require restructuring the area, but simply the elimination of fragmented free space elements (FSEs) and scraps in the root addressable area (RAA), and the movement of as many segments as possible from independent overflow (IOVF) into their respective RAA or DOVF control intervals (CIs). The reorganization function of Fast Path Reorg/EP offers a high-performance alternative for reclaiming fragmented space in a unit of work (UOW) when compared to the traditional reorganization process of unloading and reloading the DEDB area.

The reorganization function, which is executed by the REORGANIZE command, effectively takes advantage of any free space in the UOW and frees as many IOVF CIs as possible with a minimum of I/O. The reorganization function performs the following tasks:

  • Reclaims space

  • Resequences roots

  • Controls segment placement on the reorganized DEDB

  • Optionally extends the size of the IOVF and SDEP portions of an area during space reclaim without changing the DBD

Selection of UOWs with patented intelligent reorg

Certain characteristics of a UOW can determine whether reorganization of the UOW might result in significant performance improvement. Fast Path Reorg/EP incorporates the patented Intelligent Reorg technology. Intelligent Reorg selects UOWs based on certain user-specified criteria and reorganizes only those UOWs whose characteristics meet the specified criteria.

You can specify criteria to answer the following questions:

  • Does the UOW extend into IOVF?

  • Is UOW fragmentation over a specified threshold?

  • Can reorganization of the UOW save a specified amount of IOVF?

High performance is achieved by reorganizing only UOWs that meet the criteria, which saves time and resources during space reclaim maintenance.

Under ordinary conditions, not all UOWs in an area extend into and use IOVF CIs. The Intelligent Reorg feature selects only those UOWs that use IOVF, giving the greatest return with the least I/O to the area. The Intelligent Reorg feature can be turned off, allowing all UOWs to be reorganized, even if the UOW does not extend into IOVF.

Intelligent Reorg examines each UOW to determine whether it is disorganized so that only UOWs that require reorganization are reorganized. This feature reduces I/O, processing, and downtime. To efficiently perform space reclaim, the Intelligent Reorg function follows these steps:

  1. It reads each UOW of the selected area or areas.

  2. It examines the UOW to determine level of disorganization.

  3. It reorganizes the UOW only if the UOW is disorganized.

  4. It rewrites the UOW to the same data set only if more than a specified amount of IOVF space was reclaimed.

User-specified control of the reorganization

User-specified keywords let you control the DEDB reorganization process manually.

You can reorganize all areas or selected areas, and you can reorganize all UOWs or selected UOWs by using selected keywords with the REORGANIZE command.

Automatic pointer validation during reorganization

If you have a license for the Fast Path Analyzer/EP product, the product performs quick (checksum) pointer validation by default when you execute the reorganization function.

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