>>-+---------------------------------------------------------+-><
   |                .---,1---.     .---PASSDelay(999)------. |   
   '-MMOVPCT--(--n--+--------+--)--+-----------------------+-'   
                    '-,p-----'     '-PASSDelay--(--nnnn--)-'     

n

This 1- to 3-digit number specifies that DFSMSdss is to attempt to assemble up to n% of tracks as free tracks in a contiguous area. If n% is greater than the total number of free tracks available to the task, the DEFRAG operation resets this value to the number of free tracks available to the task.

p

This 1- or 2-digit number specifies that DFSMSdss is to make up to p passes in attempting to assemble the tracks. If p is not specified, only one pass is made.

PASSDelay

Specifies the time delay between the passes (p) specified in MMOVPCT(p,n). PASSDELAY is meaningful only if (p) is greater than one.

nnnn

This 1- to 4-digit number specifies the time delay in milliseconds (1/1000 of a second). When MMOVPCT (n,p) is specified and PASSDELAY is not specified, a default PASSDELAY value of 999 (almost a second) is used to allow access to the volume between MMOVPCT passes.

DEFRAG processing attempts to move a fraction of the free tracks during each pass. It calculates an integer limit that is the larger of n% of tracks divided by p or the value of 15. The limit is compared to the cumulative number of tracks moved after each extent is moved. If the limit is reached or exceeded, the current pass ends, and a new pass starts. Between each pass, the DEFRAG function releases and re-obtains volume serialization. This action can reduce the overall time in which a DEFRAG operation makes a volume unavailable to other applications.

The DEFRAG operation might end before completing p passes. If the DEFRAG operation cannot assemble n% contiguous tracks as free without moving more than n% tracks, DFSMSdss issues a message and ends the DEFRAG operation. If n% contiguous free tracks exist, the DEFRAG operation continues to reduce the fragmentation of the volume, if it can do so without relocating more than n% tracks.

The operation or the current pass also ends when DEFRAG processing criteria (for example, FRAGI) are satisfied. If you specify more than one pass, only the current pass ends. DFSMSdss issues message ADR233W for the current pass when the FRAGI criteria has been met. The DEFRAG function continues to run and attempts to complete the specified number of passes. DFSMSdss issues message ADR233W for each pass that meets the FRAGI criteria. The function continues because activity on the volume between the DEFRAG passes might change the fragmentation index and the subsequent DEFRAG passes might further reduce the fragmentation of the volume.

To restore volume serialization between DEFRAG passes, DFSMSdss uses a default value of WAIT(3,30). This means that DFSMSdss is to retry the volume serialization 30 times at 3 second intervals for a total wait time of 90 seconds. The DEFRAG operation issues a message and ends if DFSMSdss cannot obtain volume serialization; any remaining passes do not run. The WAIT option explains how to change the wait and retry values if the defaults are not suitable for your installation.

If you do not specify MMOVPCT, DFSMSdss attempts to assemble a contiguous free area of a size equal to the total number of free tracks on the volume in a single pass. The DEFRAG function uses two methods to assemble free tracks on the volume. The first method attempts to assemble the largest contiguous amount of free space with a minimum amount of data movement. The second method attempts to assemble multiple groups of large areas of contiguous free space and generally moves more data than the first method. If you specify MMOVPCT, only the first method is used during each pass.