Re: [PATCH] Move SG_GET_SCSI_ID from sg to scsi

[Alan Cox]

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.

Alan

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