RE: iSCSI: clearing SCSI objects

[wrstuden@wasabisystems.com]

On Fri, 2 May 2003, Eddy Quicksall wrote:

> Thanks for making me more aware.
>
> Actually what I'm looking for is a sure fire way I can release resources for
> a SCSI Initiator Port (InitiatorName+ISID) after session closure (assuming
> there are no outstanding persistent reservations).
>
> Understanding "I_T Nexus Loss" better brings up another point regarding
> this:
>
> Section 6.3.4 of SAM-3R6 says that the target shall establish a unit
> attention for the SCSI initiator port. But the SCSI initiator port is
> identified via the ISID. That means after a session closure (in my case via
> a session logout), the target needs to still keep state information for each
> ISID that was ever used.
>
> That can be a burden on the target's resources. Especially if the initiator
> device uses a different ISID for each login.

I don't think we need to worry about that. One of the things iSCSI has
that parallel SCSI didn't have is that you can notice when you lost the
connection. I_T nexus loss UA was needed before, since you wouldn't
necessarily notice it. Since you will notice it with iSCSI, I think we're
fine. After all, the initiator will know, and can pass such a UA up its
stack.

Note I'm assuming we're talking about cases where the initiator is just as
likely to notice the nexus loss as the target. If for some reason we could
have an I_T nexus loss w/o the initiator noticing (a nexus loss that isn't
a session loss, not sure what that'd really be), then yes, we should
assert a UA.

Take care,

Bill