Subject: Re: iSCSI : On the subject of R2T and Task Tags.

From: Raghavendra Rao <[email-masked]>
Date: Wed, 10 Jan 2001 09:45:02 -0500 (GMT)

> The "Target Transfer Tag" that you are referring to is per R2T and not per 
task.
> There is no per-task identifier that can be used by the targets to track the
> task. They will either have to :

I don't think per R2T target tag makes sense.

It would simplify if target maintains one-to-one mapping of target and initiator
task tags. So, until the task is terminated, the target should simply post the
same target task identifier in every R2T it transmits corresponding to an
initiator task tag.

-JP

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From: Santosh Rao <[email-masked]>
Date: Wed, 10 Jan 2001 14:12:08 -0800

When multiple R2Ts are outstanding, the targets need a tag per R2T to track their
SCSI State Table Entries for each R2T. While its usage depends on how each
individual programming model implements this feature, I believe the header should
provide support to track each R2T using an id that the target can lookup for its
R2T data buffer pointers.

Not having this id will cause a more expensive lookup that needs to be based on the
Buffer Offset that the WRITE Data PDUs will carry.

Implementations can choose to not use (0xFFFF) or use a single value for the Target
R2T Tag if they do not need this feature or specify MaxOutstandingR2T as 1.

- Santosh Rao