Subject: RE: [Forces-protocol] topic 2:: HA

From: "Khosravi, Hormuzd M" <[email-masked]>
Date: Wed, 28 Apr 2004 09:35:31 -0700

Weiming, Avri, Ram,

Is the compromise proposed by Jamal, myself below acceptable to you guys
?

Thanks
Hormuzd
-----Original Message-----

> > [Weiming] If there is no CE-CE comm., the CE has to do from scratch 
> > (only with
> > the FE providing some limited  state infomation). In this case, it's

> > of very
> > little help for the CE to even know who the FE used to talk with.
> 
> [ad] I agree that knowing who had been Primary (assuming there is only

> a single primary) is not as useful in this case.  Still the Fe should 
> be able to supply a rather complete picture of its state if so 
> required.

Ok, i think i finaly got what you are saying and i think it is
a valid scheme. Since we are already putting responsibility to the
FE to be aware of all CEs in multiCE setup, i dont think this additional
item will be that much of a cost either performancewise or protolwise
(there will be some cost).
OTOH, i think if a CE-CE setup decides it wants to likewise pass such
information around, that too should be fine.
I am not sure how to reach a compromise: Should the setup make the 
decision?

[HK] I agree, we can have a compromise to keep both these schemes, i.e.
FE may send events, packets to all CEs or just primary CE as
configurable. This can be a behavior which is configurable by the CE. Is
this acceptable to Avri, Weiming, others ?

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From: Robert Haas <[email-masked]>
Date: Wed, 28 Apr 2004 19:33:44 +0200

This seems to address the CE group issue I raised in my previous note, 
so I am fine with it. The CE group may consist of a single CE or 
multiple CEs. I suggest to consider symmetry, i.e., FE groups, as well.
-Robert

-- 
Robert Haas
IBM Zurich Research Laboratory
Säumerstrasse 4
CH-8803 Rüschlikon/Switzerland
phone +41-1-724-8698  fax +41-1-724-8578  http://www.zurich.ibm.com/~rha

---

From: [email-masked]
Date: Wed, 28 Apr 2004 13:48:55 -0400

Hi,

Yes, as long as the capability exists in the protocol, I don't mind if 
someone can turn it off.  I would argue, though, that having a FE 
notify its primary CE (or the CE group) of any new CE association (or 
loss of association) would be useful even if there is a CE-CE link - 
just as a safety check.  And obviously if everything is going well with 
CE coordination, then the CE probably will not need to request a state 
dump from the FE, but of course should be able to.

I also think that the ability to stifle event messages, by type 
including CE association announcements, is probably a general 
capability which is needed in any case.

a.

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From: "Wang,Weiming" <[email-masked]>
Date: Thu, 29 Apr 2004 13:54:03 +0800

Hi Avri, Rob, Hormuzd,

I actually quite agree to retain the ability at the PL for FE able to
Broad/Mulitcast to CEs regarding its events, ability change, etc, and also quite
agree with Avri's idea below. What I propose is just we may be careful when we
recommend a CE failover (HA) scheme to customers. We should not let customers
have a feeling that such B/M ability can solve HA very well. Customers should
more rely on their CE-CE implementation for this purpose, with the B/M ability
as only some asistance, therefore 'may assist fast CE failover recovery' may be
the appropriate description.

Cheers,
Weiming