[geeks] Speaking of Bad practice in the Win/X86 world

[Charles Shannon Hendrix]

On Thu, Apr 24, 2003 at 02:34:30PM -0400, Michael A. Turner wrote:
> > One of my clients was concerned that year-end processing was
> > coming up soon and the VAX had been up for over 500 days.  The
> > client wanted the system rebooted.  Never mind that there weren't
> > any problems.
> > -- 
> > Eric Dittman
> > dittman at dittman.net
>  
> 	This does actually have a sick basis in probability math. Let me see
> if I can explain this the way they are seeing it. If the chance of a server
> failing on a given day is X, and the chance of it failing the next day is X
> * 2, so at 500 days it is x * 500 and growing towards certainty. 

That's not how probability works.

Each day, a fixed probability is the same.  It doesn't increase because
of time.  Are you more likely to see a probably failure in a long
period of time?  Yes, but the chances each day are the same.

Also, rebooting a machine isn't going to decrease the probability, but
it might very well increase the chances of failure.

This is because failure is based mostly on errors, and wear.

Again, rebooting doesn't fix this, and might make it worse.

Of course, if you have bad software with memory leaks and things like
that, you might well have to reboot.

With a sane OS, you should be able to tell if there are problems like
this.


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