On Wed, 24 Apr 2002 03:46:04 +0800, John Summerfield <[EMAIL PROTECTED]> wrote:
>> 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 (o >> r >> >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. >> >> > >I do believe we used VM/PE, before MDF became available. > >We used to run two, occasionally three MVS systems on a 5860. MDF was largely equal to the LPAR facility... VM/PE had a very elegant development name: Janus - who was the Roman God of portals, able to look two directions at the same time. It was originally written by Dewayne Hendricks and the original was very nice indeed. [Anyone feel free to correct me]. I ran across an original listing while at Amdahl and it was so much prettier then the product version. He was no longer working at Amdahl by the time I arrived. Robert Lerche was also involved, but I don't know whether he worked jointly with DH or not. john
