My GDPS mate asked us to make sure that cache fast write (CFW) on out (PPRC)
mirrored boxes is disabled because it is not compatible with HyperSwap. This
statement presumes that data in the CFW is not mirrored, is it?
Up to now, I got somewhat inconsistent informtion about CFW in current DASD
subsystems. Trying to get a clear view with the help of specialist here on the
list.
I understand that CFW can be switched on/off via IDCAMS. While this can be
protected via RACF, this is not bullet proof. Some software (DFSort?) might
write its own channel programm to set the switch.
I therefore asked our DASD provider if CFW can be permanently disabled on the
box. Got a "Yes, but nobody does it"
Talking to someone else, I was told that modern DASD subsystems always use CFW;
the user has no influence in this (??)
Finally I haven't been able to figure out whether data in the CFW cache is
mirrored *before* of *after* the data has been hardened to the platter.
Appreciate any insight. Thanks in advance
--
Peter Hunkeler
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