RE: iSCSI: INQUIRY page 0x83 identifier

["Mark Bradley" <markb@indstorage.com>]

128 bits will not last as unique for very long.  It should probably
be 256 bits.  Have a look at CORBA, OLE IDs for ideas on how these
can be generated.  There's a significant body of work there.
  --  markb

> -----Original Message-----
> From: owner-ips@ece.cmu.edu [mailto:owner-ips@ece.cmu.edu]On Behalf Of
> Jim Hafner
> Sent: Monday, January 29, 2001 10:09 AM
> To: ips@ece.cmu.edu; Robert Snively
> Subject: RE: iSCSI: INQUIRY page 0x83 identifier
>
>
>
> Bob,
>
> I strongly agree with the requirement that these identifiers be WWUnique.
> But I also agree with Charles that whatever identifier that is presented
> should be the same regardless of the interconnect, so binding
> them to FC or
> to some defined iSCSI mechanism seems inappropriate.
>
> So, I think I'm agreeing the Rob Elliot.  Namely, specify a 128 format
> rooted in EUI-64 for the device. Back away from anything
> FC-specific in the
> format of the EUI-64. A vendor of a storage controller will probably have
> an EUI-64 for the device, though that might not be FC-based.  Use this as
> the basis for some vendor-specific algorithm to generate the LU
> identifier.
> Leave it to the vendor to define an algorithm that will provide the
> uniqueness.
>
> Also, I'd like to keep iSCSI from specifying any requirements on logical
> units (that's not the right space).  SPC-2/3 can spec a general format and
> the requirement for uniqueness.  Then leave it to the vendors to implement
> correctly.
>
> Does that sound reasonable?
> Jim Hafner
>
>
> Robert Snively <rsnively@brocade.com> on 01-26-2001 01:30:43 PM
>
> To:   Jim Hafner/Almaden/IBM@IBMUS, ips@ece.cmu.edu
> cc:
> Subject:  RE: iSCSI: INQUIRY page 0x83 identifier
>
>
>
> > 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.
>
>
>
>