Re: Can we build a proper email cluster? (was: Re: Why is debian.org email so unreliable?)
On Fri, 15 Oct 2004 23:33, Arnt Karlsen <arnt@c2i.net> wrote:
> > On Fri, 15 Oct 2004 03:19, Arnt Karlsen <arnt@c2i.net> wrote:
> > > > Increasing the number of machines increases the probability of one
> > > > machine failing for any given time period. Also it makes it more
> > > > difficult to debug problems as you can't always be certain of
> > > > which machine was involved.
> > >
> > > ..very true, even for aero engines. The reason the airlines like
> > > 2, 3 or even 4 rather than one jet.
> >
> > You seem to have entirely misunderstood what I wrote.
>
> ..really? Compare with your average automobile accident and
> see who has the more adequate safety philosophy.
If one machine has a probability of failure of 0.1 over a particular time
period then the probability of at least one machine failing if there are two
servers in the cluster over that same time period is 1-0.9*0.9 == 0.19.
> ..@d.o, "2 boxes watching each other" or some such, will give
> that "Ok, I'll have a look some time next week" peace of mind,
> and we don't need symmetric power here, one big and one or
> more small ones will do fine
Have you ever actually run an ISP?
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