RE: iSCSI: 2.2.6. Naming & mapping

["DeKoning, Rod" <rdekonin@lsil.com>]

Title: RE: iSCSI: 2.2.6. Naming & mapping

Since he hit one of my hot buttons regarding mapping (and therefore, discovery), . . . I heartily endorse Pierre's assertion that the Device Identification Page be used to identify Logical Units (Specifically the Volume WWN flavor).  This is extremely important in an environment that may access volumes (logical units) through many paths and potentially through multiple underlying ports or physical devices.

The only question is: does this fit in a protocol spec such as iSCSI?

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

-----Original Message-----
From: Pierre Labat [mailto:pierre_labat@hp.com]
Sent: Thursday, September 14, 2000 12:07 PM
To: ips@ece.cmu.edu
Subject: Re: iSCSI: 2.2.6. Naming & mapping

julian_satran@il.ibm.com wrote:

> Not again (what is the sign for frustration?)... I mean not before the next
> version.
>
> Julo
>
> Raghavendra Rao <Jp.Raghavendra@EBay.Sun.COM> on 14/09/2000 21:04:02
>
> Please respond to Raghavendra Rao <Jp.Raghavendra@EBay.Sun.COM>
>
> To:   Julian Satran/Haifa/IBM@IBMIL
> cc:
> Subject:  iSCSI: 2.2.6. Naming & mapping
>
> I feel that a LUN should be very much part of the Naming scheme
> that has been proposed in the draft, regardless of the level of
> enforcement of the scheme by implementors. LUNs are very much
> part of SCSI addressing, and where LUN doesn't exist, zero is
> assumed.
>
> Without a LUN identifier, Naming section doesn't look complete.
>
> Do you have insights why it is omitted ? Is this by design or overlook ?
>
> Thanks.
> -JP

About the topic of naming a LU, what seems to be  a benefit for me, is to
adopt the same requirement as fibre channel: each LU MUST provide a
unique identifier (from the Device Identification Page).
From what i read it seems that it is not a big deal to add this page in a LU.
However, this unique identifier is not needed for iSCSI protocol to work.
It doesn't interact with the protocol.

But from an administration point of view, to configure a server using storage
through iSCSI, the existence of this unique identifier helps a lot.
It allows the configuration product to know/check  if various LUNs correspond
to the same LU, it could help to manage  the  LU migration (the LUN is changed

inside a target for the same LU).
It simplifies the configuration software by avoiding it to fake a unique LU
identifier.
It will help in having a configuration tool for iSCSI that can be closer to
the one
used with FC.

Is somebody knowing if it is planned to incorporate this Device Identification
Page
in the iSCSI LU? Will it be mandatory? Which format (identifier type) will be
used?
FC  uses the type 3 (FC_PH Name_Identifier).

Regards,

Pierre