On Friday, 01/30/2009 at 09:29 EST, Kris Buelens <[email protected]> 
wrote:
> I really prefer unique volsers. 

I know I ranted on this issue recently, but it needs to be more than a 
'preference'.  z/VM is designed to run in an environment with UNIQUE 
volsers (PAV aliases are not of concern since CP understands the 
relationship).  If you don't have unique volsers, then YOU are responsible 
for system and data integrity.

This means you need to understand the implications of a copy or restore 
operation (whether DDR or FLASHCOPY) and of giving a guest access to real 
cylinder zero.  You must take precautions to ensure that such volumes are 
never seen or felt by CP except at your explicit discretion.  Always 
assume that your system will restart at the worst possible moment or that 
there may be a coup d'machine and someone else may take charge of the I/O 
subsystem. (DR, anyone?)  And, of course, we know that Other People make 
mistakes!  :-)

Alan Altmark
z/VM Development
IBM Endicott

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