Robert Jennings wrote:
What I meant that is that the kernel tgt code (scsi_tgt*) receives
SCSI commands from one lld and send them to another lld instead of
sending them to user space.
Although the approach of passing SCSI commands from a target LLD to an
initiator one without any significant interventions from the target
software looks to be nice and simple, you should realize how limited,
unsafe and illegal it is, since it badly violates SCSI specs.
I think that 'implemented cleanly' means that one scsi_host is assigned
to only one initiator.
Vladislav listed a number of issues that are inherent in an implementation
that does not have a 1:1 relationship of initiators to targets. The vscsi
architecture defines the 1:1 relationship; it's imposible to have more
than one initiator per target.
Just few small notes:
1. As I already wrote, complete 1:1 relationship isn't practically
possible, because there is always a local access on the target (i.e. one
more initiator) and you can't disable it on practice.
2. 1:1 relationship is a serious limitation for usage cases like an SPI
tape library serving backup for several servers on an FC net.
Vlad
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