🚀 go-pugleaf

> >>Okay, but what about the situation of one satellite vaxstation on a lightly
> >>loaded network?  I think page read I/O's should be considered separately
 from
> >>page write I/O's.  Does this satellite system do page read I/O's any faster
> >>over the ethernet versus to local disk?  [I would imagine that page write
> >>I/O's would be dependent entirely on the relative disk speeds of the local
> >>versus boot node disk speed.]
> >
> >Nope.  The local disk's still faster.  When I and a friend did VMS tuning
> >studies for <a former employer> we found that even on an unloaded net the
> >local disk was faster.  Mind you, this was using VAXstation IIs with between
> >5 and 16MB and RD54s.  Mileage on newer systems may vary, but I'd bet that
> >the local disk still beats Ethernet traffic.
> >
>
> Depends on your hardware. We have a VAX 4000 model 500 with RF35's serving a
> bunch of VS3100's, some with disks (RZ23) and some without. I can assure you
> that the local disk is not faster in this situation. I had a diskless 3100
> paging to the 4500 for a while; the machine is now at my house and has a local
> RZ57 as a standalone system. It most definitely *felt* faster when it was
 paging
> to the 4500; I have no measurements on this, however (except that an RF35 is
> waaaaay quicker than an RZ57).

I think, that two important aspects has been left out of this discussion.

A fast server-machine with a fast disk may be much faster than a local disk,
if the server is doing nothing else.

But often such a powerfull server will often support many workstations and
if they are all active, then performance may decrease a lot.

Another common configuration is to have a general purpose machine as a server.
A VAX 65x0 with RA92's may be a good server if it is empty, but if it has
80 interactive users it may be a rather slow server.

So the question about what is fastest local or remote disk depends both on the
server power AND the load on the server.

One conclusion may be, that a local page-file will make the user of the
workstation less dependent of other activities, which may be considered
an advantage.

                                                          Arne

Arne Vajhxj                             local DECNET:  KO::ARNE
Computer Department                     PSI:           PSI%23831001304030::ARNE
Business School of Southern Denmark     Internet:      ARNE@KO.HHS.DK