SUMMARY (addendum): SCSI disk for Sun4/280

From: Hanh Vu - xt 2801 (
Date: Thu Mar 05 1992 - 21:53:04 CST

This is an addendum to my SUMMARY as I just received new info
from another Sun manager on this great list.

Original posting (excerpt):
> > Is it possible to connect an external SCSI disk to a Sun4/280
> > and get reliable performance? i.e. what happens if I
> > connect a disk with transfer rate of 2.0MB/s to a controller
> > with max transfer rate of 1.5MB/s. Will data just pass at
> > 1.5MB/s or will some of it be consistently lost?
> >

Original SUMMARY:
> The experience from several system administrators indicate that
> it is possible to connect a faster SCSI disk to the Sun4/280
> controller without data loss. Although the SCSI controller
> is rated at 1.5MB/s, it can buffer data to/from the device.
> The disks mentioned by the repliers to my questions however,
> are in the < 2.5MB/s transfer rate, so although these replies
> answer my question satisfactorily, I am unsure if this would
> apply to disks with much higher transfer rates than 1.5MB/s
> (4+MB/s).

No data will be lost even though the rated transfer speed between
the controller and drive vastly differ. This is because they can
negotiate at what speed they will transfer data (and what mode--sync
or async) to/from each other. The set-back is that data will be
exchanged at the lower speed, and the higher performance capability
of the faster disk will be wasted.

Many thanks to Kevin Sheehan ( for this
final wrap-up.

| Hanh Vu | |
| Dept. of Computer Science and Engineering | Internet: |
| Florida Atlantic University | Office: (407) 367-2801 |
| Boca Raton, FL 33431 USA | Fax: (407) 367-2800 |

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