On Tue, Jan 11, 2005 at 03:40:47PM -0500, Brian Cuttler wrote:
> 
> Amanda user list,
> 
> I've spoken to Harry at Condre systems and he confirmed what we
> where seeing. The jukebox robot is a narrow bus so that are two
> changes we need to make.
> 
> 1) We want to move the jukebox/SDLT to be the last device on
>    the daisy chain.
> 
> 2) We want to terminate the jukebox-robot, so we need to make
>    certain that the live port on the box hits the SDLT before
>    we reach (electically) the robot.
> 
> Hopefully this will have a positive effect on both SDLT drives.

Not a scsi expert here, but if you terminate the jukebox, wouldn't
that terminate only the narrow portion of the bus leaving the extra
lines of the wide bus unterminated.  Might there be some kind of
device/cable to go from wide -> narrow terminating the unused lines?

Also, I think that if both types of devices exist on the same bus,
the lower performance one determines the performance of the entire
bus.  That narrow jukebox may hurt your sdlt performance just by
being on the bus.  Some of my scsi adapters have multiple channels
and buses.  Perhaps you could run the sdlt's on one channel, wide,
and the jukebox on another, narrow or wide.  I added a cheap second
controller from a dead system for a very similar purpose, external
devices that were narrow when the main controller was driving only
wide devices.  Its two channels were used for different speed devices.

jl
-- 
Jon H. LaBadie                  jon AT jgcomp DOT com
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