Alan,

We have been using our current DASD setup for about 5 months now, with no 
problems, until a couple of days ago. We have 896 (256+256+256+128) devices on 
the Escon channels, using 4 control units, which PTK shows as 3990-6. AFAIK 
this should all be nicely within the IBM and EMC limits.  
What puzzles me is that we do millions of IOs to all those devices, but the 
problem only occurs with the IPL command in a virtual machine. Is there some 
special kind of IO involved with IPL? 

Thanks,
Geert.
_____________________________
Geert Dieltiens
Systeembeheerder
Informatica J. Van Breda & C°
Tel.: + 32 3 217 50 16


-----Original Message-----
From: The IBM z/VM Operating System [mailto:[email protected]] On Behalf 
Of Alan Altmark
Sent: woensdag 25 maart 2009 16:33
To: [email protected]
Subject: Re: FW: IPL 190 hangs in zVM 5.4

On Wednesday, 03/25/2009 at 03:54 EDT, Dieltiens Geert 
<[email protected]> wrote:

> I made that device available to a VM in another LPAR on the same CEC, 
and there 
> the IPL worked.
> Our 3 LPARs share the same Escon channels to an EMC box. Each LPAR only 
uses 
> it's own set of DASD devices (the other devices are set offline 
according to 
> SYSTEM CONFIG "OFFLINE_AT_IPL").
> 
> In the production LPAR I see msgs like this on the OPERATOR console:
> HCPMHT2153I DASD  B03C I/O CANCELLED DUE TO A MISSING INTERRUPT
> They started appearing since the moment that I IPL'd another VM in 
another LPAR 
> last weekend. I thought that maybe some devices were being used in both 
LPARs, 
> but I checked, and that's not the case.
> 
> Maybe EMC can find out more...

I have seen odd I/O incidents (tho not on EMC) when the number of devices 
defined in an I/O configuration exceeds the number supported by the 
control unit.  E.g. every dasd chpid with every device on the chpid 
defined to all the LPARs.  As soon as a device "beyond the limit" is used, 
it pulls the device away from whoever had it first.

But working it through EMC will be good.

Alan Altmark
z/VM Development
IBM Endicott
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