On 12/03/2016 07:58 AM, esmie moo wrote:
> Gentle Readers,
>
> I have a question about FLASHCOPY using ADRDSSU and COPY. In my first
> example I was told that the job is using FLASHCOPY. However I do not see any
> evidence.
>
> COPY FULL INDYNAM (SDB000) OUTDYNAM (MDB000) DUMPCONDITIONING
> ADR101I (R/I)-RI01 (01), TASKID 001 HAS BEEN ASSIGNED TO COMMAND 'COPY '
>
> >From my understanding it is performing a full volume copy of a source
> >volume. If my understanding of the parm DUMPCONDITIONING is correct, it
> >(DUMPCONDITIONING) allows to make a copy of the source volume and while
> >keeping the target volume online.
>
> I have done a full volume copy of a source to target without the
> DUMPCONDITIONING parm and it worked - the volume was fully copied (see
> below). Am I missing something? Aren't both examples doing the same thing?
>
>
> COPY INDDNAME(DASD1) OUTDDNAME(DASD2) -
> ALLDATA(*) ALLEXCP COPYVOLID PURGE
> /*
>
> However I do not see any evidence of FLASHCOPY being invoked because the FCNC
> parm is not present.
>
> Here is a my second example:
>
> COPY FULL IDY(PROM70,3390) ODY(SNAP63,3390) DUMPCOND FCNC-
> ALLDATA(*) ALLEXCP CANCELERROR PURGE FCTOPPRCPRIMARY -
> FCSETGTOK(FAILRELATION)
>
> In the above example FLASCHOPY is being performed because of the FCNC.
>
> Could you correct my understanding of all 3 examples?
>
> Thanks.
>
>
If you do a full volume copy without DUMPCONDITIONING and with
COPYVOLID, that means when the copy is complete the target volume will
now have the same VOLSER as the source volume and dss will force it
offline, as you can't have two volumes with identical VOLSER online to
the same MVS system. If your goal was just to make a point-in-time
copy on DASD, that may be sufficient. But if your goal was to then back
up that target volume to removable tape media, you would not be able to
do that with dss from the same system because the volume is offline
because of the duplicate VOLSER. It also means that if you for some
reason needed to IPL at that point, the system will complain about
finding two volumes with the same VOLSER and there could be some
confusion about which of the two volumes should be placed online and the
wrong one could be chosen.
With DUMPCONDITIONING the original different target volume VOLSER is
preserved so both volumes can be online to the same system and there is
no later confusion about which is the original and which is the
point-in-time copy. DSS is smart enough when restoring from a tape dump
of the volume with the DUMPCONDITIONING copy to also restore the
original VOLSER (this used to require either an VTOCINDEX or VVDS
dataset on the volume to supply the correct VOLSER).
There are other vendor utilities that will allow one to dump an offline
DASD volume with a duplicate volser to tape, but this seems to me a
perversion of the meaning of "offline", which was intended to mean
access by the system was impossible and that the device could safely be
taken physically offline for hardware maintenance.
Assuming there is still a dss FASTREPLICATION parameter, it used to
default to "PREFERRED", which meant if flashcopy wasn't available for
some reason, dss would default to an ordinary copy but still do the COPY
command successfully (just m-u-c-h slower). If you wanted the copy to
fail if flashcopy were not possible, you had to explicitly request
FASTREPLICATION(REQUIRED). It should be obvious from the time required
for the COPY command to complete whether flashcopy has been used: a
fraction of a second for the dss COPY command to complete with fastcopy,
versus minutes without fastcopy.
Joel C. Ewing
--
Joel C. Ewing, Bentonville, AR [email protected]
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