Re: [PATCH] Move SG_GET_SCSI_ID from sg to scsi

From: Douglas Gilbert <dougg@torque.net>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Linus Torvalds <torvalds@osdl.org>,
	Matthew Wilcox <matthew@wil.cx>, Bodo Eggert <7eggert@gmx.de>,
	linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Move SG_GET_SCSI_ID from sg to scsi
Date: Mon, 27 Mar 2006 16:29:13 -0500	[thread overview]
Message-ID: <44285929.4020806@torque.net> (raw)
In-Reply-To: <1143489287.4970.76.camel@localhost.localdomain>

Alan Cox wrote:
> On Llu, 2006-03-27 at 09:43 -0800, Linus Torvalds wrote:
> 
>>The fact is, BUS/ID/LUN crap really doesn't make sense for the majority of 
>>devices out there. Never has, never will. The fact that old-fashioned SCSI 
>>devices think of themselves that way has absolutely zero to do with 
>>reality today.
> 
> 
> It is still a very visible reality if you work in a data centre or with
> server kit, or if you have tape arrays or multi-CD towers. The LUN or
> device number in particular are generally the number emblazoned on each
> slot in the unit and knowing the LUN reliably is sort of critical to not
> making embarrasing (and career limiting) screwups when swapping drives.
> 
> Controller is a pretty abstract concept and except on arrays so is
> device, but both device and LUN do need to be accessible reliably for
> the hardware that thinks that way. What other hardware does is
> irrelevant and "-EINVAL" seems as good an answer as anything.

USB multi-card readers seem to like the concept of
LUNs as well.

Doug Gilbert
"What, never? Well, hardly ever." G+S HMS Pinafore