Re: SAM-2 LUN Level definition

[Ralph Weber <ralphoweber@compuserve.com>]

The dependent logical unit addressing in SAM-2 derives from
the SCSI Controller Commands (SCC-2), see:

 ftp://ftp.t10.org/t10/drafts/scc2/scc2r04.pdf

T10 feels that the model is more generally useful than just
SCC-2, which explains its presence in SAM-2.  This opinion
has not yet reached full maturity so the cloud nature of
things is not surprising.

I cannot comment on the interactions of the Peripheral
Addressing mode and iSCSI.

Ralph...

Sanjeev Bhagat wrote:

>
> * From the T10 Reflector (t10@t10.org), posted by:
> * "Sanjeev Bhagat" <iscsi_t10@sanjeevbhagat.com>
> *
> Hello,
>
> I was going carefully through the LUN level definition of SAM-2 specs.
> Although everything seems to be fine, but i have a very basic question.
>
> Can somebody explain me , why is the following has  been designed so.May be
> I am missing something
>
> WHY is a 4 level structure defined at all?? Except for the fact that more
> devices can be connected to the same SCSI TARGET DEVICE, i dont find any
> other reason for it. Moreover the way the command is proceeded further to
> other LUN levels is also a bit shady in the sense that the LUN level
> structure has to be modified everytime the command is sent to lower levels.
>
> The Peripheral device addressing method does not allow for addressing scsi
> LU's not on the same level.
>
> If we choose for Device specific addressing methods then it will basically
> make it not inter-operabel with all the other SCSI initiator/target devices
> in the world.
>
> Regards,
> Sanjeev
>
> *
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