Tom,

FWIW, we too had a corrupt Dynam 7.0 catalog, in 2005. 

First, we got the advise from CA about not using caching/MDC for Dynam
catalog MDISKs and like you I had my doubts about it but just to be on
the safe side I coded NOMDC for the MDISK for the Dynam catalog in the
production VM.  
But in our development VM (with 3 busy VSE guests) I've always used MDC
for the Dynam catalog MDISK and never had any problem with it. 
The hardware cache (3990 controllers in EMC Symmetrix) has always been
active AFAIK.

Then, we found out that during a backup-restore of the Dynam catalog,
the catalog got dequeued to soon. While reviewing the logs, to my
surprise, I saw that *another* batchjob had been able to update the
catalog simultaneously with the restore, causing the corruption. That
other job issued CADD014W CATLG. ERR. R/C=0C100000 FILE=xxxxxxx, but
apparantly the damage had been done.
We then received ptf T705710 from CA (which is now available as "QO72105
DYNCAT - Prevent dequeue during RESTORE REORG"), applied it and never
had that problem again. If you are current on Dynam service, then it's
probably on your system already.

I also remember a mandatory SHARE=YES parameter when initialising a
shared Dynam catalog.

But you probably went thru all that with CA.

Bye,
Geert.


-----Original Message-----
From: The IBM z/VM Operating System [mailto:[email protected]] On
Behalf Of Tom Duerbusch
Sent: dinsdag 28 juli 2009 19:52
To: [email protected]
Subject: IBM DS6800 caching

Can cache be turned off for a volume on the DS6800?

I don't think so.  But I would like to confirm that.

Tom Duerbusch
THD Consulting
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