[8524] in linux-scsi channel archive
Re: Fast Wide vs Ultra Wide
daemon@ATHENA.MIT.EDU (Ricky Beam)
Tue Apr 4 00:45:24 2000
Date: Tue, 4 Apr 2000 00:36:52 -0400 (EDT)
From: Ricky Beam <jfbeam@bluetopia.net>
To: Matthew Dharm <mdharm-scsi@one-eyed-alien.net>
Cc: The Linux SCSI list <linux-scsi@vger.rutgers.edu>
In-Reply-To: <Pine.LNX.4.10.10004031116040.10344-100000@ziggy.one-eyed-alien.net>
Message-ID: <Pine.LNX.4.04.10004040027370.23096-100000@beaker>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
On Mon, 3 Apr 2000, Matthew Dharm wrote:
>Can an Ultra Wide SCSI-II drive operated when attached to a Fast Wide
>SCSI-II controller? I have this setup (all components purchased 2nd
>hand), and it's not working. I'm trying to figure out what part of all
>this (controller, cable, drive) is bad.
If (and that's really _IF_) the manufacture bothers to follow the rules
(read: the SCSI2 specs) then the answer is yes. All SCSI hardware is
_supposed_ to be fully backwards compatible all the way back to 5MHz,
8bit wide, async transfers. (That, btw, is the speed of the command
channel -- someone said 4MHz. Only the data in/out phases run at high(er)
speeds.)
That does not mean everyone follows the rules. I have a few IBM drives that
power up in LVD mode on a SE bus -- they aren't supposed to do that -- and
remain in LVD mode until they are addressed in a SE fashion; this trashes
the bus until they switch to SE (note: I have placed the idiot jumper on
them to force them into SE _always_.)
--Ricky
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