RE: iscsi: rev 05 2.5.1 requires ACA support

[Black_David@emc.com]

> Even with management commands, position within the command stream is
> assumed.  Should there be commands sent without an ability to verify
> relative position and with the potential for excessive skews between
> connections, the use of a zero seems clumsy.  It could apply to command
not
> yet received on different connections.  Even though a command may have a
> sequence value, it could be 'Marked' for immediate use without strict
> adherence to sequence.  The sequence value could be used to filter late
> comers, perhaps the cause for the management command in the first place.
> The task attribute could be used to understand if there is a need for
> immediate application or an iSCSI specific bit if that is too difficult.

This sounds like what ordered delivery is currently specified to do,
possibly
coupled with a note to implementers suggesting that task management
commands be executed promptly after delivery to SCSI.  An example of
a scenario that may work with immediate delivery ("use of a zero" above)
is one in which some person or piece of software has determined or
suspects that something undesirable is going on in/at the target device
and wants it stopped NOW!!! (e.g., "What on earth is that tape robot
doing???").

--David
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David L. Black, Senior Technologist
EMC Corporation, 42 South St., Hopkinton, MA  01748
+1 (508) 435-1000 x75140     FAX: +1 (508) 497-8500
black_david@emc.com       Mobile: +1 (978) 394-7754
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