HP P9000 for Compatible FlashCopy Mirroring User Guide (AV400-96388, October 2011)

Optimization of Volumes
Volumes can be optimized by Compatible FlashCopy, if you use the DEFRAG command of the
DFSMSdss utility with the FASTREPLICATION option. See the IBM manual for details of the option.
CAUTION: The DEFRAG command may generate an error because the number of relationships
per volume exceeds the maximum when all the following conditions are met.
• The parity group including the volume is overloaded with many accesses.
• The DEFRAG command is executed with FASTREPLICATION(REQUIRED).
To avoid an error, avoid using the FASTREPLICATION option or specify
FASTREPLICATION(PREFERRED). If you specify FASTREPLICATION(REQUIRED), reduce workloads
on the parity group.
28 About Compatible FlashCopy operations