Re: iSCSI Autosense Consensus, Connection next steps

["Randall R. Stewart" <randall@stewart.chicago.il.us>]

Stephen Bailey wrote:
> 
> > Second, on connections, I haven't seen enough discussion to call
> > consensus, but I am going to try to narrow the option space and
> > structure the discussion.  Four models for sessions have been
> > proposed:
> >
> > (1) Symmetric - all connections usable for command and data.
> > (2) Asymmetric - single command connection, others are data.
> > (3) Split - assign LUN sets to specific connections or pools of
> >       connections.
> > (4) SCTP - use SCTP's support for multiple connections.
> 
> For the purposes of shaping the consensus, here's my stance:
> 
>   1) SCTP should only be pursued if TCP does not admit a viable
>      solution to the iSCSI requirements.
> 
> Given that there are many iSCSI community participants expressing the
> belief that iSCSI on TCP IS possible, I believe iSCSI on SCTP
> proponents are just going to be stuck holding an `I told you so'
> card.
> 

I would rather have it in the spec and a option and then not have
to say "I told you so" but instead say .. lets go try it with SCTP
since it is allowed...

> This gates my second statement:
> 
>   2) multiple connections per session should only be supported if the
>      underlying transport (e.g. SCTP) layer supports it.
> 
> Obviously, TCP does not presently support this abstraction, so
> assuming SCTP gets killed for now, I am against multiple connections
> per session.

I strongly concur here. We can NOT have multiple TCP connections and
be able to stay TCP friendly to the rest of the internet...

R

> 
> In general, I am dubious that connection bundling above the transport
> layer, but below some more application-informed layer (e.g. a wedge
> driver) will work acceptably.  However, if the transport layer
> provides it, then, by definition, it must work (ha, ha), or at least
> it's not iSCSI's place to say that it won't.
> 
> Steph

-- 
Randall R. Stewart
randall@stewart.chicago.il.us or rrs@cisco.com
815-342-5222 (cell) 815-477-2127 (work)