From: Arrigo Triulzi (arrigo@northsea.sevenseas.org)
Date: Fri Jun 03 2005 - 15:25:16 EDT
Dear all,
I have inherited a DS20 with a three-channel KZPAC controller (a.k.a.
Mylex DAC960) with the following setup using the internal disk bay:
2x 9Gb in a RAID 1
4x 9Gb in a RAID 5
This works wonderfully well and a recent Linux distribution
(Debian/sarge) happily runs on it. I have now been asked to connect a
BA356 to the box which houses 2x 9Gb and 4x 19Gb disks and my cunning
plan was to use the external connectors at the back of the KZPAC to
connect it.
After digging through my memory (it has been a long time since I last
installed one of these babies) I recalled that there's an issue
regarding how the buses are split on the KZPAC and in particular on the
DS20 the built-in disk bay is actually not on a single SCSI channel but
split over two channels. I also checked in the KZPAC manuals and the
two connectors at the back are channel 0 & 1 respectively basically
extending the internal buses. The other spare internal connector on
the KZPAC is channel 2 which can be "pulled" out via a suitable option
which I don't have...
The BA356 is also in split-bus configuration, i.e. there's two SCSI
cables coming out of it and if I connect it to the KZPAC directly and
try to bring up the system I get a failure on the internal disks losing
disks 2 & 4 (counting from 0) on the internal bay and disks 2 & 4
(again counting from 0) on the external BA356. That indicated to me
that there's an obvious SCSI ID conflict which is to be expected given
the split-bus configuration on the DS20... I can see only three disks
(1,3,5) but can't see 0 at all for some reason (might be dead, green
light is on though but the KZPAC management s/w can't see it).
Note that the KZPAC sees all the internal disks as the first column
(channel 0) so I might be talking totally out of my backside on the
DS20 split bus and the issue is "simply" one of setting the BA356 dip
switches to turn it into a single channel and then stick that into the
external channel 1 port (where it sees the three disks in the BA356
already). I _think_ I have figured out where the dip switches are via
the BA356 user's guide found via Google but any further guidance or
caveats would be greatly appreciated).
So, my question to the gurus is which is my best course of action at
this point bearing in mind that ideally I wouldn't want to reinstall
the whole system (it is running as an Amanda backup server with an SDLT
and doing a very fine job but needs some extra staging space)?
To make matters more complicated I only have a remote serial console
via serial concentrator onto the box with a pair of kind but totally
unexperienced hands on-site.
Thanks in advance.
Ciao,
Arrigo
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