Expectations or It can't happen to me (was Re: How Reliable)

[Sean Donelan <sean () donelan com>]

On Wed, 25 Feb 2004, Bora Akyol wrote:
> It needs to be as reliable as the services that depend on it.
>
> E.g. if bank A is using the Internet exclusively without
> leased line back up to run its ATMs, or to interface with
> its customers, then it needs to be VERY reliable.

That's not very reliable.  On a "normal" day, 95% of the cash machines are
working nationwide.  Telephones, E911, hospitals, nuclear power plants
have a variety of "normal" failures all the time.

Humans are traditionally very bad at understanding risk.

> As more and more critical services/infrastructure moves
> to the IP/MPLS, the expectations in terms of reliability
> go up every year. The real questions are:
>
> * How much are the customer's willing to pay for it?
> * What kind of reporting/management infrastructure we have
> to enforce/monitor the reliability commitment in the SLA?

Unfortunately, both of those are marketing issues and have very
little to do with actual reliability.

One very well-known ISP had a "premium" Internet service that only cost
30% more than its standard Internet service with a 100% SLA.  What
you received was the same service with an insurance policy.  If the
service met the SLA you paid 30% more, if it didn't you only paid the
standard price.

Does buying travel insurance change the risk of the plane crashing?