Subject: iSCSI:Text field in Asynchronous Message

From: "Kaladhar Voruganti" <[email-masked]>
Date: Wed, 13 Jun 2001 18:49:09 +0100

Will there ever be a need for a Target to send an asynchronous Text message
to the initiators (for potential performance optimizations)?

According to the current iSCSI specification, the initiators can send Text
messages to the target.
Moreover, the initiators can send vendor specific X- key/values to the
target.

Now, why can't the targets also have the ability to send X-key/value pairs
to the initiators via Asynch messages?
I would like input from people as to whether this feature will be useful.

Thanks,
Kaladhar Voruganti

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From: Stephen Bailey <[email-masked]>
Date: Thu, 21 Jun 2001 13:08:23 -0400

> Both iSCSI and SRP have native Asynchronous Event Reporting IUs which can be
> used for this type of purpose.

I guess my point is that FCP doesn't, and it's the only currently
deployed SAN solution.

Beyond that, some SCSI stacks (Solaris, unless they've changed
something recently....), don't provide support for clients to receive
SCSI AENs.

In other words, the useful support for SCSI AEN is patchy.  I'm not
arguing that AEN support shouldn't be provided by a transport.  I am
arguing that if you want your (target) solution to work on many
platforms and transports, you might chose not to use AEN.  Prominent
target vendors (e.g. LSI/Symbios) have taken this route.

Steph

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From: Stephen Bailey <[email-masked]>
Date: Fri, 22 Jun 2001 21:28:33 -0400

Bob,

> In general, none of the initiators have a process in place to do
> anything with an AEN.

Ah, but in specific, CAM-based initiators (Tru64) DO have support for
this.  I don't know if *BSD (or Netware?) chose to implement SET ASYNC
CALLBACK or not.  AEN handling such a strong differentiator, I expect
Compaq Alphas overtake Sun and HP in the 64-bit server market within
the year :^)

Steph