From: ulowell!cg-atla!weber@harvard.UUCP (Jeff Weber)
Newsgroups: comp.sys.sun
Subject: Re: Emulex MD21 vs. Adaptec ACB4000
Message-ID: <6901@cg-atla.UUCP>
Date: 24 Apr 89 04:24:59 GMT
Approved: Sun-Spots@rice.edu
X-Sun-Spots-Digest: Volume 7, Issue 242, message 2 of 16

aad@stepstone.com (Anthony A. Datri) writes:
>I see that there are different sets of supported disks under these two
>controller types in Sun's 4.0 format.dat file.  The Micropolis 1355 is
>listed under the MD21, yet I have a Sun sheobox with a 1355 attached to an
>Adaptec.  Is this division as arbitrary as it seems?  I want to take a DEC
>rd53 (really a Micropolis 1325), and hang it as the second drive off of
>the MD21 in a Sun shoebox that already has a 1355 in it.  I suspect that
>this'll work just fine as long as I add an entry for the 1325 off of the
>MD21.

Interconnect stuff deleted...

First off the MD-21 is a SCSI to ESDI controller and abotu twice as fast
as the Adaptec 4000 which is a SCSI to St-506 controller.  ST-506 and ESDI
are traditionally disk interfaces and ESDI is twice as fast as ST-506
(send nit contradictions to /dev/null).

You cannot intermix the drive and controllers just because the cables fit,
which they do.  I'm pretty sure that experimentation will lead to the
purchase of a disk or controller.  A 1355 is a 327MB(f) ESDI disk and a
1325 is a ~85MB(f) ST-506 disk.

MD-21's don't like to have two different configurations of disks attached
let alone an ST-506 added in for good measure.  I'd check that you have a
1355 ESDI connected to a ST-506 Adaptec.  Something is not right is that
is INDEED the situation (is it really a Adaptec 4000?) and not some
non-4000 controller.

	Jeff Weber