RE: iSCSI:flow control, acknowledgement, and a deterministic recovery

["Douglas Otis" <dotis@sanlight.net>]

David,

> > To not support rejects, you are then relying on the target to
> > handle these now out of sequence commands.
>
> Immediate commands are "out of sequence" by definition - immediate
> means deliver immediately without regard to CmdSN order.  Only the
> target can do this, so I don't see any problem with relying on the Target
> to do so.

The commands that are NOW out of sequence are those commands bypassed by the
immediate command.  If this immediate command was Rewind, then a long list
of write commands become invalid as a new tape is now needed for those
operations.  You are expecting that the target to handle a long list of
invalid commands made possible by the iSCSI sequencer.  Commands invalidated
by immediate commands become out of sequence commands.

I'll reserve further comment until Julian has made some progress in
addressing these concerns.  I also suspect it is a mistake to allow commands
to remain trapped within the sequencer during emergency or abnormal events
signified by the use of these immediate commands.

Forgive my advocacy, but if one does not attempt to support a position, then
the subject is not explored.

Doug