Response Summary Re: Performance data needed for third party disks

From: Stephen Carr (
Date: Thu Jun 14 1990 - 16:31:23 CDT

My apologies for taking so long to post this summary. I received only
two replies, the first, a rather detailed discussion of the relative
merits of SMD, ESDI and SCSI disks and controllers, indicated that in
terms of real performance, (ie. buffered read and write operations as
opposed to raw disk IO) syncrounous, caching SCSI disks and
controllers can perform as well as many SMD disk/controller
configurations. However, an SMD configuration which also takes
advantage of interleaved seeks and command caching will still
outperform the best SCSI. The second response was a reminder that
there are several manufacturers of NFS accelerators which can improve
NFS server performance.

Unfortunately neither of these responses actually addressed my
original question regarding whether or not a Sun 4/260 has the CPU
power to take advantage of the performance advantage of an SMD
disk/controller. After some prolonged monitoring of actual CPU
utilization under typical load conditions, we have determined that
processor power will not be the limiting component for the
configuration I described and that the disk/controller interface is

I have appended my original request; many thanks to both Peter Berens
at Apunix and Jon Zeeff both of whom responded to my original posting.
If there is enough interest in the performance data which I mentioned
above, I will request permission from the authors to repost the data to this
list. Again, Much thanks to all respondents.

I'm sure that this has been discussed before and I apologize for
bringing it up again but...

I've been asked to evaluate the relative performance merits of
SMD and synchronous SCSI disks. My configuration is:

        Sun 4/260
        SunOS 4.0.3 (soon to be upgraded to 4.1)
        16 Mbytes of Sun memory
        16 Mbytes of Clearpoint memory
        Xylogics 451 SMD controller with two 327 Mbyte drives
        Xylogics 713 ESDI controller with two Hp97548E 793 Mbyte drives

I've been asked to upgrade this machine two a four gigabyte NFS file
server. The Xylogics 713 and Hp97548E's will be moved to another
machine. Proposed alternatives are the purchase of a Xylogics 7053
and four Imprimi 1.2 gigabyte drives or the purchase of either an
Interphase or Ciprico synchronous SCSI controller and either 4
Imprimi 1.2 gigabyte drives or 4 Hp 1.2 gigabytes synchronous SCSI

In terms of raw speed, no doubt the SMD's will out perform the SCSI's.
The question that's been raised here is whether or not the 4/260 has
the prerequisite MIPS to take advantage of the SMD's speed advantage
or if we will be CPU bound by NFS activity and lose the performance
advantage of the SMD's. If this is likely to be the case, we might as
well take advantage of the cost savings that the SCSI's offer.

This machine will be utilized pretty exclusively as a NFS file server (no
NFS swap partitions or other heavy sources of network activity;
network consists of approximately 60 workstations), and it will be
utilized only by one user (SA who doesn't often get to do any serious
hacking). Has anybody got any hard performance data on a similar
configuration (smaller memory configurations or a 4/280 comparison
would be considered valuable) with either SMD drives or synchronous
SCSI's? I will gladly summarize back to the net.

Steve Carr Internet:
Icad, Inc. Phone : (617) 868-2800
1000 Massachusetts Avenue
Cambridge, MA 02138

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