[8243] in linux-scsi channel archive
Re: New to U2W/LVD and termination
daemon@ATHENA.MIT.EDU (Ricky Beam)
Fri Feb 25 13:52:25 2000
Date: Fri, 25 Feb 2000 13:44:09 -0500 (EST)
From: Ricky Beam <jfbeam@bluetopia.net>
To: Brendan Miller <brmiller@netgate.net>
Cc: linux-scsi@vger.rutgers.edu
In-Reply-To: <20000224220545.A28357@netgate.net>
Message-ID: <Pine.LNX.4.04.10002251337120.12259-100000@beaker>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
On Thu, 24 Feb 2000, Brendan Miller wrote:
>... Now most U2W drives can run in
>"UW, single-ended" compatibility mode, right? This one seems to,
s/most/all/ or so requires T10. (I've never read anything in the specs
to suggest otherwise. But the specs are not yet in stone. Altho', as I
understand, they have been sent to the stone cutter.)
>as per both the IBM docs (it's a Ultrastar 18ES, DNES-309170), but
A truely excellent drive -- and amazingly cheap.
>the new thing I learned was that these drives don't retain the
>ability to terminate the bus themselves. Instead, you must provide
>internal termination on the last plug of the ribbon cable--something
>I've never done before.
Correct. LVD capable drives to do not have on-board termination logic.
They can provide power to the bus to run a terminator, but they do not
have the resistors them selves. (Termination has become much more involved
in modern times.)
>I'm only running the drive in single-ended mode, so a single-ended,
>active terminator would work, right? If I get an LVD controller
>someday, would I use one of the LVD terminators? Is there a terminator
>I can buy today that will work in both single-ended and LVD
>applications?
Yes. Yes. and Yes. The LVD multi-mode active terminator is your best
answer -- of course, they are also in the 100$US range. If you can get
one with the controller, it makes the 150$US much better spent.
--Ricky
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