RE: iSCSI: INQUIRY page 0x83 identifier

[Robert Snively <rsnively@Brocade.COM>]

> As for an iSCSI type or format for logical unit identifiers:
> 1) SCSI already allows for an ascii formatted identifier (typically this
> includes vendor, model, serial number). Since NDT has defined WWUIs for
> DEVICES and these have a defined UTF-8 format, there is nothing to
> *prevent* a vendor from using these strings as the starting point for LU
> page 83 identifiers of the logical units within that device.
> 2) But..., iSCSI and NDT should not attempt to make a rule under which
> these are used.  FC's intervention in this was more as a strong suggestion,
> and is certainly not a requirement.

Jim,

I generally agree with the text of your comments, but there are
a couple of details I would like to address.  

Any name not based on a registered entity and in a registered format
is not guaranteed to be world-wide unique, and is therefore 
inappropriate.  That is why numbers like OUIs and SCSI Vendor IDs 
in specified parts of the identifier are a requirement.  EUI-64
and FC identifiers have that property.  FC identifiers have the added
benefit of having a regular extension capability for dynamic creation
of logical units.  As you point out, iSCSI need not use FC
identifiers, but a bunch of people like them for their constant 
defined length and guaranteed world-wide unique identifiers.

However, I feel that iSCSI should be a lot more hard nosed than
SAM-2 and require that VPD page "83" contain a mandatory world-wide
unique logical unit identifier in an appropriate invariant format.
For compatibility with other SCSI drivers, it should be limited
to 128 bits of length.  This would not be an identifier set by
the user (there are other SCSI identifiers that can be set by the
user), but one that is invariant from the time of manufacture (for
physical devices) or creation (for logical devices) of the logical unit.