RE: iSCSI: INQUIRY page 0x83 identifier

[Patrick Stirling <pms@veritas.com>]

On Fri, 26 Jan 2001, Michael Krause wrote:

> At 01:30 PM 1/26/2001 -0800, Robert Snively wrote:
>
> >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.
> 
> Why not just require EUI-64 which is a very large name space and is / will 
> be used in many hardware solutions today / future?  This would also fit in 
> well with other I/O standards that use EUI-64 for identifying all I/O 
> components / controllers.  Having a 128-bit value seems like overkill and 
> provides little benefit.

Well, I'd prefer to stick with the current scheme of allowing the device
to specify its identifier within certain limits (table 181 in spc2r18).

I'm working on a virtual storage server, which serves up virtual disks on
the fibre-channel SAN (with iSCSI coming soon I expect). We set just this
identifier in VPD page 0x83, using a type 3 identifier (FC-PH) - actually
a Registered Extended IEEE Name, 128bits. It's convenient to use this
length as it allows me to set the upper 64bits to our server's WWN (which
is also used as the World-Wide Node Name shared by all target HBAs on the
server), and the lower 64bits to a simple number identifying the virtual
disk on this server.

This makes it easy to set an identifier which is guaranteed unique
world-wide, although it does have the drawback of making it hard to
keep the id if you move the virtual disk's data to another server.

With the formatting of the various identifiers, 64 bits doesn't go very
far at all.

patrick
Patrick Stirling
VERITAS Software Corporation
pms@veritas.com