Re: [PATCH RFC 2/2] implement transport scan callout for iscsi

[James Bottomley <James.Bottomley@SteelEye.com>]

On Tue, 2005-05-24 at 14:01 -0700, Mike Christie wrote:
> > It's a leading transport connection of the session1 (above). Quoting the
> > spec (http://www.faqs.org/rfcs/rfc3720.html):
> > 
> >    - According to [SAM2], the I_T nexus is a relationship
> >      between a SCSI Initiator Port and a SCSI Target Port.  For iSCSI,
> >      this relationship is a session, defined as a relationship between
> >      an iSCSI Initiator's end of the session (SCSI Initiator Port) and
> >      the iSCSI Target's Portal Group.  
> > 
> > The session itself is not a "physical connection"; it aggregates one or more
> > transport connections between a given SCSI Initiator Port and a SCSI Target
> > Port. There is always at least one (leading) connection.
> > 
> 
> So just to be clear, open-iscsi can support multiple connections per 
> session. Do you want us to completely remove this feature for mainline? 
> I know you and christoph have given me this answer many times before, 
> but not seeing a reply to Nicholas's question about just disabling may 
> have created some doubt as to the extent people have to go? Since 
> open-iscsi pushed the connection management code to userspace, removing 
> MCS from the driver will not be too terrible a job for us though.
> 
> The connection dir for single connection sessions though is just a nice 
> way to export the kernel structure's info and have it also reflect the 
> iSCSI RFC's definitions at the same time. For sfnet we used to throw 
> everything in one dir becuase it did not have a connection structure so 
> it simplified refcounting.

My current position on MC/S is that it runs counter to the no multi-
pathing in the drivers policy, so should not be done.

As far as I can see it's an optional add on to the iSCSI standard which
doesn't improve the feature set or provide any value add over the
mandatory explicit multi-path support in rfc3720, which is easy to do
via dm-multipath.

James