On Thursday, 07/27/2006 at 02:46 AST, David Boyes <[EMAIL PROTECTED]>
wrote:
> > > >Then again, if you have a z9, you probably don't much care. 8-)
> > what about performance and CPU overheads (zVM) in processing I/O's, is
> > it an issue?
>
> It (the difference between dedicated and minidisk I/O) is measurable,
> but the impact is smaller on the z9 systems due to the increased
> processor speed.
>
> I'm sure the Velocity folks will chime in with more details.

I/O assist was only available with V=R and V=F guests while running in
basic mode, so any improvement was limited to those 6 virtual machines.
For a Linux farm, the vast majority of guests (V=V) never benefitted from
I/O assist.  And starting with the z990 there is no basic mode, so even
the Big Six get no benefit.

That, plus the removal of preferred guest support (V=R and V=F) from z/VM
V5, the loss of I/O assist on the processor doesn't mean much.

Alan Altmark
z/VM Development
IBM Endicott

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