Re: Can we build a proper email cluster? (was: Re: Why is debian.org email so unreliable?)

[Arnt Karlsen <arnt@c2i.net>]

On Sat, 16 Oct 2004 21:29:32 +1000, Russell wrote in message 
<[🔎] 200410162129.32843.russell@coker.com.au>:

> 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?

..no, I'm an aeronautical engineer and likes Zeppeliners.  ;-)

-- 
..med vennlig hilsen = with Kind Regards from Arnt... ;-)
...with a number of polar bear hunters in his ancestry...
  Scenarios always come in sets of three: 
  best case, worst case, and just in case.