Re: iSCSI : EnableACA

[julian_satran@il.ibm.com]

Ralph,

I am not sure that I understand the question.

After the reset task management functions iSCSI requires the target enter
Unit Atention for all other initiators connected to the same target (or LU)
and, after reporting the Unit Attention enter ACA.

You and Ed pointed out that many initiators will be unable to handle this
(will not reset the condition).

EnableACA is a hack intended to allow an initiator to control the target
behavior.

NormACA and the NACA CDB bit have similar purposes but NormACA is a
"read-only" flag and the ACA condition is not created in this case as a
result of a command execution error but as a result of an action by an
external factor (another initiator).

This situation is probably more general - and some other transports dealing
with commands in flight might experience a similar
problem but up to now SPC has no way of handling this situation.

If Ed is going to cover this within the "extended use of ACA" we discussed
for SCSI commands rejected with busy and task set full and for Unit
Attention we might have to coordinate.

Regards,
Julo



Ralph Weber <ralphoweber@compuserve.com> on 27/04/2001 14:59:24

Please respond to ENDL_TX@computer.org

To:   Julian Satran/Haifa/IBM@IBMIL
cc:   ips@ece.cmu.edu
Subject:  Re: iSCSI : EnableACA




Julian,

Regarding your discussion with Santosh...

> The task management functions for iSCSI contain a
> description the behaviour I am talking about. This
> was also subject to a long discussion on the list
> that included the need for ACA behaviour for things
> like task-set full, busy etc. - not considered for
> ACA. For the later T10 is handling making ACA
> behaviour available.
>
My question is... Exactly which what are the cases where
T10 is NOT considering making ACA behavior available so
that you believe the EnableACA function is necessary in
iSCSI?

My belief is that every behavior that EnableACA covers
but T10 does not needs to be taken to T10 to see if
they can find a better way to extend ACA coverage to
that area.

Thanks.

Ralph...