SRP and login with initiator port identifier already in use
Edward A. Gardner
eag at ophidian.com
Wed May 23 19:57:31 PDT 2001
* From the T10 Reflector (t10 at t10.org), posted by:
* "Edward A. Gardner" <eag at ophidian.com>
I think I agree with Bob Nixon's response. The following is somewhat more
Multiple independent paths between the same initiator and target ports (the
same I_T nexus) mean just that. They are between the *same* initiator and
target ports -- that is, there is only one initiator port and only one
target port. Done confuse these with ports on IB adapters.
It's analogous to FCP with a fabric that uses multiple paths and therefore
provides out of order delivery. Except that the multiple paths / channels
are visible to the initiator, so it can choose on a request by request basis
whether to enforce ordering (use the same path/channel) or allow out of
order behavior for performance (use any path/channel).
>The logical units behind the target treat the login as if a separate
>initiator port identifier were being used. In most regards, everything
>comes in would run independently.
False. All the paths have the same initiator port identifier. All are part
of the same I_T nexus. All share the same reservation, persistent
reservation and UA context. One could also send a command down one path,
then abort it with an ABORT TASK down the other. There's a race condition
with this, I don't recommend it, but one could do this -- might make a good
compliance test :-).
>If a reservation has been established, however, the permission would be
>checked only on the initiator port identifier sent during login. Thus one
>reservation can apply to multiple "initiator ports".
It is true that "permission would be checked only on the initiator port
identifier sent during login". That is the *only* initiator port identifier
that exists. True, the reservation may apply to multiple paths/channels,
which may involve multiple IB adapters and/or ports. But those are *not*
SCSI initiator ports.
>UAs and other things for "other initiators" would treat this new channel
>nexus as having a different initiator.
False. It's the same initiator port.
Edward A. Gardner eag at ophidian.com
Ophidian Designs 719 593-8866 voice
1262 Hofstead Terrace 719 593-8989 fax
Colorado Springs, CO 80907 719 210-7200 cell
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