> >There should still be write inhibit "switch" for a volume, even if 
> only a logical one. It can be very useful, when running under z/VM, 
> to be able to define some z/OS volumes as read-only. It would be 
> nice if you could do something similar in a z/OS LPAR.
> 
> Amen. We could really use this feature. It could be an option when 
> defining devices in the IOCP.

  z/VM intercepts every SSCH done by its guests, and
examines/modifies the guest channel programs.  LPAR does not
routinely intercept guest SSCH.  So it would likely not
be reasonable for LPAR to provide a write inhibit switch 
for a device.

 z/OS does scan and modify DASD channel programs, so it might 
be reasonable to have DASD UCB switch which says to set the 
mask byte in the Define Extent (or analogous command)
parameter to inhibit all write operations. 

Jim Mulder   z/OS System Test   IBM Corp.  Poughkeepsie,  NY

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