DFSMS can outperform DDR: it has an OPTIMIZE option that varies from 1 to 4. With the fastest setting, DFSMS reads a whole cylinder with one I/O. DDR never reads more than a single track. But, this also means DFSMS -with enough workers- can drive the channel usage to about 100% and the responsetimes of your system become very bad...
The DFSMS COPY command can only copy CMS formatted minidisks and only if the target has at least the same number of blocks as the source. It is much faster than FORMAT & COPYFILE as formatting and copying is done at the same time, if the target is larger, the extra blocks are simply formatted and DFSMS will update some CMS control information after which you still have to run a FORMAT (RECOMP to set everything straight. DFSMS COPY can be issued just like any simple CMS command, no servers involved, you need to link the source and target minidisk. The DFSMS MOVE command at the other side submits work to SMSMASTR which dispatches it to DGTSRVxx machines. The DGTSRVxx workers talk to DIRMAINT (or a similar directory maintainer product) to allocate space for the target minidisk. Then the DGTSRVxx workers copy the minidisk using DFSMS COPY or FORMAT & COPYFILE if the target is smaller or has another blocksize. DFSMS's ISPF interface will result in DFSMS MOVE commands. My DRM/DRMGUI tool allows to change the size of moved minidisks, it displays how full CMS minidisks are (if you have LINK permissions) so you can judge. Kris, IBM Belgium, VM customer support
