On 11/09/2012 5:41 PM, Bruno Sugliani wrote:
Everyone WOULD ... but how many do ? On this list for example? just curious There is a difference between theory and real life. My 20 years in IBM level 2 support center gave me some scars. Several customers have been very sorry to use a single CP machine. Running to the HMC to make a PSW restart because of a spin loop was no fun and generally too late :-)) . AFAIK one of the reason for models with capped engine ( while single or double full cap engines would have been sufficient) was in part because of single engine side effects. ( at the expense of some batch run time ).
Single CP z/OS systems? I would guess maybe 1/3 to 1/2 of the systems I have worked on were single CP. And yes I have some scars :-)
It's interesting, a few years ago I had the chance to talk to one of the people involved in developing WLM and asked about single CP systems. His reply was "Don't do it. z/OS is designed for multiple CPs." However, my experience is that there are a lot of people who do run smaller systems as single CPs. I guess the larger sites with bigger systems are more visible inside IBM.
WLM is very sensitive to the policy on a single CP system. You will quickly discover any problems with the policy, and looping work is a danger. Anything in SYSSTC needs to be VERY well behaved. But going from one to 2 CPs for the same capacity you lose 50% of your engine speed. And I think smaller systems often tend to have more single threaded work.
BTW can you have a spin loop on a single CP system? I thought spin loops were waits for something held by another CP.
Andrew Rowley -- and...@blackhillsoftware.com +61 413 302 386 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
