On Tue, 23 Apr 2002 05:32:03 +0800, John Summerfield <[EMAIL PROTECTED]> wrote:
>> > ... >> >This is nothing really new. Sharing a VM system with early releases of >> >MVS was unpleasant. >> >> I hear that it's no problem with the two in different LPARs, and that >> running MVS as a guest under VM works well with a surprisingly small >> performance hit (in the 2-3% ballpark.) >> -- >> --henry schaffer >> > >In the times when "Sharing a VM system with early releases of MVS was >unpleasant," IBM hadn't invented LPARs and I think Gene had just released (or >was about to release) the S/470s. > > >MVS+VM, I was told, made the 168 comparable in performance to a 135. One of my first projects at Amdahl was supporting a product called VM/PE, a boringly named, technically cool piece of software which shared the real (UP) system between VM and MVS. S/370 achitecture is dependent on page zero and this code swapped page zeros between MVS and VM. It worked just fine for dedicated channels, nice low 1-2% overhead. When we started sharing control units and devices, things turned ugly. Of course PR/SM which turned into the LPAR facility... and a parallel Amdal 580 feature obsoleted the software in 4-5 years. john alvord
