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From Aleksey Yakovlev <aleksey.yakov...@gmail.com>
Subject Re: Zookeeper on two clusters?
Date Fri, 26 Aug 2011 23:17:19 GMT
Ted, Camille:

My example with files sending is just one most evident example. My scripts
need to talk to each other as well. For example, "I'm exiting with code 99,
so all the guys waiting for me - please stop waiting - I'll revive with a
new identity (which I don't know now) - please wait for a signal ABC and you
will know"

I didn't look into any messaging system yet. My biggest problem is
connectivity (load balancers, bastions etc. - please see my starting memo),
so I'm exploring various possibilities trying to understand their
flexibility and requirements to connectivity

BTW, what is "coordination system" exactly? I'd like to see a definition


On Fri, Aug 26, 2011 at 6:24 PM, Ted Dunning <ted.dunning@gmail.com> wrote:

> Camille's comment is exactly correct.  Why not use a messaging system
> instead of a coordination system.
> Also, if you don't know the exact requirements, then you cannot
> successfully
> use ZK (or a screwdriver) to meet those requirements.
> You are correct that loosely coupled distributed systems are very
> difficult.
>  This is related to the fact that with tightly coupled systems you can
> (sort
> of) ignore some of the failure modes for the most part and your system will
> still appear to work (much of the time).
> The way that I like to say this is that the cost of a Now is largely
> determined by its diameter and time scale.  A very large Now costs
> exponentially more than a very small Now.  Getting Now on the scale of 5 mm
> is pretty cheap.  At 5 m, the cost is significant, but not massive.  At
> 5000
> km, it is very expensive to get a Now better than 50ms.

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