Path: utzoo!attcan!uunet!lll-winken!lll-tis!helios.ee.lbl.gov!nosc!ucsd!ucsdhub!hp-sdd!hplabs!hpda!hpcupt1!hprndlb!kc
From: kc@hprndlb.HP.COM (Kurt Chan)
Newsgroups: comp.periphs
Subject: Re: Re: Questions on SCSI device interfacing...
Message-ID: <4740003@hprndlb.HP.COM>
Date: 8 Sep 88 06:32:33 GMT
References: <8551@cup.portal.com>
Organization: HP Roseville Networks Division
Lines: 20

> The best thing to do is have all initiators (host adapters -- there may be
> more than one) provide TERMPWR through a diode and a fuse.  This is what
> SCSI-2 requires...
         ^^^^^^^^

Do you recall the reason for this requirement?  Bob and I were discussing a
solution to one of our system problems that involves making sure one and only
one source of TERMPWR exists on the bus.  

By taking TERMPWR away from other initiators (removing the fuse) we have
more predictability in terms of which devices experience RST on a cable
disconnect, since the termination network will ground all the lines, including
RST, when TERMPWR is lost.  

By keeping other initiators (yes I know, even other hosts) from providing
TERMPWR, our on-line-replacement procedure is a bit easier.

Kurt Chan
HP, Roseville Networks

(waiting for my PC to come so I can use the SCSI BB more effectively)