[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

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?

http://www.coker.com.au/selinux/   My NSA Security Enhanced Linux packages
http://www.coker.com.au/bonnie++/  Bonnie++ hard drive benchmark
http://www.coker.com.au/postal/    Postal SMTP/POP benchmark
http://www.coker.com.au/~russell/  My home page

Reply to: