[rds-devel] Re: RDS ACKs

[Richard Frank]

Yes - RDS was designed to meet Oracle's IPC requirements and I assume 
anyone else dealing with the same issues.

RDS is continuing to evolve ( RDS v3 is in dev).

We can consider publishing a more generic requirements doc - other than 
the early proposal we handed out a few years back (for RDS v1).

 From an interface perspective - we need to check in the man pages for 
RDS - if not already there.

Or Gerlitz wrote:
> Zach Brown wrote:
>>> So RDS has ACKs, correct? are they in the level of the transport (IB,
>>> TCP) or at the RDS level?
>
>> Yes, they're at the level of the transport.  The TCP RDS transport
>> derives them from TCP ACKs, it doesn't have explicit messages.  The IB
>> transport has explicit messages to indicate to the sender when a given
>> message is stable in the receiver's memory.
>
> OK, got it, and thanks for pointing me this difference between TCP to 
> IB ACKs. Now, since the RDS IB transport is implemented over IB RC 
> transport, my initial thought is that you need not use --any-- 
> software timeout mechanism for the reliability you want, this is b/c 
> either the message would be delivered to the remote memory or 
> something bad will happen. That is the RC QP would move to the error 
> state as of completion with error of some work request, etc. So you 
> only need to keep queue of non acked messages, remove from the queue 
> ones that were acked, and retransmit all of them when you re-connect - 
> am I correct?
>
>> This design comes straight from the Oracle DB networking guys.  I'm not
>> the best person to defend the design, though I can certainly share my
>> understanding of it and how the RDS kernel code is built for it.
>
> I see. The thing is that there's no requirements document nor 
> specification document nor sw design document so you are kind of the 
> only source of information for this protocol - thanks for the help!
>
> Or.
>
>
>
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