Re: iSCSI: 2.2.6. Naming & mapping

[Peter Johansson <PJohansson@ACM.org>]

At 07:45 PM 9/16/00, John Hufferd/San Jose/IBM wrote:

>As with Fibre Channel (and even multiple SCSI buss connections), once you 
>have acuired a connection to the Storage Controller, you may address  LU 
>0, to get the LU numbers that are authorize to that connection (with some 
>Storage Controllers these are virtual Devices authorized by connection 
>"port" and/or WWN of the initiator).  The values returned by the LU0 query 
>are the unique LUNs related to that LU 0  (real or virtual).
>
>The Host SCSI layer can then obtain a unique ID from the EVPD page 83h. 
>When the same unique ID is found on different paths then they have 
>discovered an "Alternate Path".   All of this is normal SCSI, not transport.

This is one of two methods I mentioned, an approach rooted in the command 
set. I have no disagreement with the usefulness of vital product data for 
this purpose.

>Since many Storage Controller create virtual volumes, and these are only 
>visable to authorized Initiators,  and also unknown to the transport. It 
>seems that we should keep to the same approach used by Fibre Channel et. 
>al. and keep it away from the (iSCSI) transport.

I was unaware that iSCSI was targeted (no pun intended) solely at Storage 
Controllers. If there are iSCSI methods to describe the existence of a 
particular target's LUs PRIOR to session establishment, then it may also be 
desirable to be able to discover unique IDs at a target or LU level at the 
same time. Some clients may find it useful to make a decision at this 
earlier point rather than after issuing a SCSI command. In any case, this 
feature would be OPTIONAL and complementary to EVPD.




Regards,

Peter Johansson

Congruent Software, Inc.
98 Colorado Avenue
Berkeley, CA  94707

(510) 527-3926
(510) 527-3856 FAX

PJohansson@ACM.org