On Wednesday, 07/29/2009 at 11:52 EDT, Tom Duerbusch 
<[email protected]> wrote:

> However, CA is saying that the root cause of our DYNAM catalog 
corruption is 
> caching.

Not impossible, of course, but highly unlikely.  If all I/O is coming down 
the same chpid from the same VM system, the cache isn't relevant, so you 
could vary offline all but one chpid.

> Where I can see if some VSE systems are accessing the DYNAM catalog thru 
some 
> sort of cache while other systems are not....big problem here.
> 
> But single VM system with MDC turned on for all, with the IBM DS6800 
with 
> caching being mandatory (I believe), shouldn't cause problems.
> 
> I turned off MDC for the DYNAM shared disks and our corruption problem 
> continues.  So they wanted caching turned off in the controller for the 
DYNAM 
> disks.  I don't think that is going to happen.

Possibly you have other MDISK statements rather than LINKs, and one has 
MDC and the other doesn't?  Tell CP the volume is SHARED and all MDC for 
the volume will be disabled, regardless of directory settings or SET 
commands. 

Alan Altmark
z/VM Development
IBM Endicott

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