[Q] DS20+KZPAC+BA356 installation issue

From: Arrigo Triulzi (arrigo_at_northsea.sevenseas.org)
Date: 06/03/05

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    Date: Fri, 03 Jun 2005 21:25:16 +0200
To: tru64-unix-managers@ornl.gov

    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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