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Limits of reliability or is 99.999999999% realistic

  • From: Toby_Williams
  • Date: Mon Nov 27 05:22:16 2000

SLAs are the point where commercial & operational worlds collide. The numbers
being offered should:

Reflect the targeted quality of the service
Tie in with meaningful damages for not achieving them

In a market where I can offer 99.7% or 100% and the difference is a whole day's
service credit, I know what I'd be offering. No question.

If on the other hand, the expectation is that I pay out a year's contract value
in cash upfront every time I miss a target in a month, then I'd only want to
offer a target that will *always* be achieved.

In the market at the moment, the situation is much closer to the first scenario
than the second - ie damages for SLAs do not mean anything to either:

the buyer, as compensation for not receiving the service that they have
contracted for;
the seller as a motivation to work within the targets, because capped service
credit agreements do not touch the bottom line

Today, in the IP market, it is irrelevant whether services come with 99.0 or
99.99999 SLAs & at some point the market needs to address the responsibility
that if they are to offer a service of a certain "guaranteed" quality, then they
should stand-by that guarantee with their money and give this guarantee meaning.

I don't think this is the case at the moment, and that's why we even see 100%
SLA in the market - because the level of pay-outs on SLAs don't matter to the

No. I'm not suggesting that sellers offer guarantees for consequential losses.
Simply ones that:

1. give the buyer the peace of mind that if the service they've contracted to is
below par, that they will have enough money put back in their pocket for them to
have replaced their service, like-for-like in the market, to cover themselves
over the period.

2. enable the market players to truly differentiate their service offerings by
quality, rather than marketing.

[std. disclaimer of responsiblity here]

Date: 25 Nov 2000 20:24:48 -0800
From: Sean Donelan <[email protected]>
Subject: Limits of reliability or is 99.999999999% realistic

<snipped for brevity>

But back to my question.  What is the real requirement?  Amazon.COM had
system problems on Friday, and their site was unusuable for 30 minutes,
definitely not 99.999%.  But what did that really mean?  The FAA loses
its radar for several hours in various parts of the country.  What did
that really mean?  Essentially every system given as an example of "high-
availability, high-reliability" I've looked at, doesn't hold up under
close examination.

Is 99.999% just F.U.D. created by consultants?

Instead of pretending we can build systems which will never fail, should
we work on a realistic understanding of what can be delivered?