QBUS SCSI card...

From: Zane H. Healy <healyzh_at_aracnet.com>
Date: Mon Feb 24 19:26:00 2003

Doc wrote:
> On Mon, 24 Feb 2003, Zane H. Healy wrote:
> > By a remote disk, I assume you're talking about a 3.5" SCSI disk sitting in
> > a remote VMS or *BSD box? In such a configuration you still should (if
> > possible) have a local swap disk.
> I know that's the standard wisdom, but the read/write speeds of all
> the MFM disks I've tried on my RQDX3s are significantly slower than
> network reads and writes.

That's interesting. I'd really not taken the slowness of the MFM disks into
account. It also makes a certain sense. Besides come to think of it, that
"standard wisdom" is generally applied to VAXstation 3100 or 4000 class
systems. Though I've been known to recommend booting a VAX 6000 class
system off of a VAXstation 4000/vlc.

> I did some not-horribly-scientific testing on my MVIII around that.
> Local disk-to-disk transfers (in NetBSD) are *much* slower than NFS-NFS
> operations, even when the NFS fs were on 2 different machines, and
> memory-intensive operations (starting an X desktop with fvwm for remote
> display) were about 15% faster *without* local swap.
> I recognize the possibility that the NetBSD drivers may have a lot to
> do with that, but my VMS skills are not up to setting up that kind of
> benchmarks.
> This was all on a KA-650 CPU, 13MB RAM, RQDX3 w/RD54, and a DEQNA
> ethernet board. I used a 16MB swap file on the NFS server.

You're making me wish I could give this a try under VMS. I wonder where on
earth I've got my pair of RD54's stashed. I know where everything else is
that would be required to temporarily switch a PDP-11 over to a MicroVAX II.
It would make for some interesting testing, and I've been wanting to us a
MicroVAX II to practice my system tuning skills (improvements are more
noticable on a MVII).

Received on Mon Feb 24 2003 - 19:26:00 GMT

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