Personal experience follows: take with a grain of salt, YMMV, may induce headaches in pregnant men, etc
It seems to me that when dirmaint is left at defaults for flashcopy behavior 2 that it appears to adopt a polling process to check whether the storage device has actually finished copying the volume in the background before returning from DVHDXD. It essentially turns the instantaneous point in time copy to a synchronous copy, like a fast DDR. There is yet another parameter you can fiddle with to adjust this behavior: DVHDXD_FLASHCOPY_COMPLETION_WAIT = <integer> <integer> Ive got mine set to "DVHDXD_FLASHCOPY_COMPLETION_WAIT = 0 0" because I noticed that my dirmaint clone disk operations were not completing much faster than a good ole DDR. >From * z/VM V5R3.0 Directory Maintenance Facility Tailoring and Administration Guide* : " These values specify when, in number of seconds, to issue a subsequent FLASHCOPY command to check for possible completion of a prior command. The first value is the wait between issuances of a CP FLASHCOPY 0 0 request, and the second is between issuances of a CP FLASHCOPY END END request. Optimum performance is 0 0 - but this should not be used if the installation has any FLASHCOPY Version 1 DASD. " Note the warning about having any FC1 storage controllers - I have no idea what happens if you try running this with FC1, but I would bet that it is bad. Probably sounds like "data integrity issues" I think this is in there as a check against a sequence like this getting issued: FLASHCOPY 1111 0 end 2222 0 end FLASHCOPY 2222 0 end 3333 0 end FLASHCOPY 3333 0 end 4444 0 end That sequence probably works with FC2, probably does not with FC1 -- Jay Brenneman
