Computer Drive User Manual

Appendix A. Concurrent Copy 513
With the target within the same logical subsystem or DS6000 as the source and
FlashCopy installed, DFSMSdss will start a FlashCopy copy process instead of
Concurrent Copy.
So, you get a FlashCopy invocation with a DFSMSdss COPY FULL command even if the
CONCurrent (or CC) parameter is coded in the command.
The FASTREPLICATION parameter of the COPY command does not affect Concurrent
Copy; it only applies for FlashCopy and SnapShot invocation.
FASTREPLICATION(REQuired) and CONCURRENT cannot be used together in the same
COPY command.
Sizing and requirements
Concurrent Copy requirements and information about sizing the storage requirements can be
found in manual z/OS DFSMS Advanced Copy Services, SC35-0428.
Central and expanded storage
Running many Concurrent Copy jobs simultaneously can cause auxiliary (AUX) storage
shortages. PTF OW50284 introduced methods to limit the amount of auxiliary storage used
and will appropriately either terminate existing CC jobs, or will fail to copy data sets using
Concurrent Copy. SDM provides the ability to modify the Concurrent Copy AUX values that
are used in evaluating the AUX storage that is used by Concurrent Copy.
Example A-1 shows the system command for modifying the Concurrent Copy AUX delta to
determine at what percentage value new Concurrent Copy data sets will not be copied using
Concurrent Copy. SDM subtracts this delta value from the lower MVS percentage. The newly
computed SDM percentage is then compared to the total current system AUX storage
percentage being used. The default value is -1, indicating that SDM will not perform a
percentage check for AUX storage usage by Concurrent Copy. The nnnn value may be any
non-negative value (including zero).
Example: A-1 Modifying auxiliary storage delta for new Concurrent Copy data set
F ANTMAIN,P .CMTUN+3A X’FFFF’ X’nnnn’
Example A-2 shows the system command for modifying the Concurrent Copy AUX delta to
determine at what percentage value existing Concurrent Copy data sets will be terminated.
SDM subtracts this delta value from the upper MVS percentage. The newly computed SDM
percentage is then compared to the total current system AUX storage percentage being used.
The default value is -1, indicating that SDM will not perform a percentage check for AUX
storage usage by Concurrent Copy. The nnnn value can be any non-negative value (including
zero).
Example: A-2 Modifying auxiliary storage delta for existing Concurrent Copy data set
F ANTMAIN,P .CMTUN+3C X’FFFF’ X’nnnn’
Production and performance considerations
When planning to use Concurrent Copy, you will be paying attention to system performance
considerations such as:
򐂰 Application response time
򐂰 Storage subsystem utilization
򐂰 System throughput