RE: iSCSI Naming and Discovery

[julian_satran@il.ibm.com]

Well I'll try to be more explicit and answers Rod's note:

Given that an FC gateway is FCP aware it can issue the relevant queries and
cache results to
avoid the query penalty at ever access.  However I think that even this is
excessive unless somebody
intends to build virtual control units composed of a multidude of
controllers beyond a gateway.

Julo

"DeKoning, Rod" <rdekonin@lsil.com> on 06/10/2000 17:09:53

Please respond to "DeKoning, Rod" <rdekonin@lsil.com>

To:   Julian Satran/Haifa/IBM@IBMIL, ips@ece.cmu.edu
cc:
Subject:  RE: iSCSI Naming and Discovery




Please keep in mind that the Logical Unit Number (LUN) is nothing more than
a handle that means nothing without the context of the Initiator/Target.
SCSI defines a nexus as a combination of the Initiator - Target - LUN.
This
nexus defines a path to a Logical Unit.  The recently introduced Access
Control mechanisms are designed to allow a host to provide several
features,
including:

1. The ability to map the same LUN to multiple Logical Units within a
target
to respective different hosts.
2. The ability to map the same Logical Unit to multiple LUNs within a
target
to respective different hosts.

These mechanisms imply that the LUN identifier must be taken within the
context of the INQUIRY VPD Page 83 volume WWN.

Regards

Rod DeKoning
Manager Storage Solutions Architecture
LSI Logic Storage Systems Inc.
ph:316-636-8842
fax:x8889
rod.dekoning@lsil.com


-----Original Message-----
From: julian_satran@il.ibm.com [mailto:julian_satran@il.ibm.com]
Sent: Friday, October 06, 2000 3:47 AM
To: ips@ece.cmu.edu
Subject: RE: iSCSI Naming and Discovery




Joshua & John,

If the troublesome item is for a "knowledgeable" gateway to to FC to get a
hold on LUNs
then this can be done within the current draft.
The LUN in the PDUs is an 8byte "object" opaque to iSCSI.
An initiator can choose to put there a WWN to be replaced (rewritten) by
the gateway with
a LUN or nay such commbination.  This operation is stateless.

Julo

"Joshua Tseng/Nishan Systems" <joshua.tseng@NishanSystems.com> on
05/10/2000 22:26:01

Please respond to "Joshua Tseng/Nishan Systems"
      <joshua.tseng@NishanSystems.com>

To:   ips@ece.cmu.edu
cc:    (bcc: Julian Satran/Haifa/IBM)
Subject:  RE: iSCSI Naming and Discovery




John,

>Joshua,
>I think the LU being part of the "/Modifier" is a bit problematical.  You
>should focus on the connections each end, and let the LU stuff be
>transparent to your Gateway.  They will of course use Report LUNs and
>Inquiry and use their approprate LU number, I am having problems
>understanding why a gateway would need to know the LU number.
>
>Could you resend your note without the LUN stuff so that we can see, a
>little easier, what you think is really needed.

You are right...my bad.  The LUN is carried in the iSCSI PDU.
What is needed in the Fibre Channel World Wide Port Name (WWPN),
which the gateway will need in order to address the Fibre Channel
device.  The gateway/proxy should register this attribute key in
the name server (yes Doug--an LDAP-based server) for retrieval by
the iSCSI initiator, who can use it in the /modifier when addressing
the Fibre Channel target.

Josh




 - att1.htm