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Date:      Mon, 15 Apr 2002 16:12:48 -0600
From:      "Kenneth D. Merry" <ken@kdm.org>
To:        "Justin T. Gibbs" <gibbs@scsiguy.com>
Cc:        mjacob@feral.com, scsi@FreeBSD.ORG
Subject:   Re: is there a reason that da should *not* drive type STORAGE ARRAY
Message-ID:  <20020415161248.A72009@panzer.kdm.org>
In-Reply-To: <200204152144.g3FLih983892@aslan.scsiguy.com>; from gibbs@scsiguy.com on Mon, Apr 15, 2002 at 03:44:43PM -0600
References:  <Pine.BSF.4.21.0204151439290.62590-100000@beppo> <200204152144.g3FLih983892@aslan.scsiguy.com>

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On Mon, Apr 15, 2002 at 15:44:43 -0600, Justin T. Gibbs wrote:
> >
> >Whilst dorking with an HP XP-512 storage arrage array on Fibre Channel, I
> >found that it defaults to type STORAGE ARRAY (not DIRECT ACCESS). However, the
> >DIRECT ACCESS commands work fine.
> >
> >Is there a reason why da(4) should *not* drive devices of type STORAGE ARRAY?
> 
> Fear of the unknown.  What differentiates a STORAGE ARRAY from any
> other DIRECT ACCESS device?  Is the assumption that they are essentially
> the same always valid?

The da(4) driver doesn't attach to storage array (type 0xc) devices because
they aren't supposed to be direct access type devices, at least in the
generic case.

If they're supposed to act like direct access devices, they should report
inquiry data that indicates that, I think.  This is from section 5.2.1.1 of
the SCC-2 (rev 04) draft:

=============
"All SCSI storage arrays shall accept LUN_Z as a valid address. For SCSI
storage arrays LUN_Z shall be the logical unit that an application client
addresses to configure an SCSI storage array and to determine
information about the target and the logical units contained within the
target. INQUIRY commands sent to LUN_Z shall return standard inquiry data
with the SCCS bit set to one (See SCSI Primary Commands - 2). If
the LUN_Z supports only the array controller commands defined within this
standard, INQUIRY commands sent to LUN_Z shall return a device type of
array controller device.  Otherwise, INQUIRY commands sent to LUN_Z shall
return a device type indicating the model defining the additional commands
supported.  Support for LUN_Z with a device type other than array controller
device is vendor specific.

The peripheral device address method shall be used when addressing the
LUN_Z of an SCSI storage array (see 5.2.1.2.3)."
=============

So it looks like it should be reporting a type of direct access, with the
SCCS bit turned on.

You might want to see whether there is some mode you can turn on in the
controller to make it expose the arrays it manages.  (Or have it tell the
OS it is a direct access device instead of a storage array device.)

Ken
-- 
Kenneth Merry
ken@kdm.org

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