[trustable-software] No silent failures?

[Colin Robbins]

Hello Duncan,

 

>From my perspective your logic holds true.

It emphasises the need to good monitoring and testing to assure that systems are working as expected (thus 3 layers of redundancy).

 

Regards,

 

 

Colin Robbins

Qonex (the consulting arm of Nexor)

Tel: +44 (0) 115 953 5541 

 

From: trustable-software [mailto:trustable-software-bounces at lists.veristac.io] On Behalf Of Duncan Hart
Sent: 25 July 2016 22:34
To: Discussion about trustable software engineering <trustable-software at lists.veristac.io>
Subject: [trustable-software] No silent failures?

 

​Hello folks,

 

I'm wondering if you good folks could help develop my thinking further....

 

I have come to accept that silent component failure is a contributor to system failure like no other. 

 

  Imagine you have a system with 3-way redundancy :

 

  If one component fails then nothing bad happens.

 

  Even if 2 components fail nothing bad happens.

 

  But if the first, and the first and second fail AND you don't know that they have, then on the one hand the redundancy can be said to be effective and, on the other hand, each failure that you do not notice, because the redundancy is covering you, brings you one step closer to an entire system failure.

 

  When an entire system failure occurs, you will declaim that it was impossible because you have (had) 3-way redundancy, but you didn't. You once did, then you had 2-way, then no redundancy at all, then you had a failure.

 

Does the logic hold true? How might this manifest itself in a software environment?

 

Thoughts, comments, feedback much appreciated.

 

Warmest regards,

  Duncan

 

 

<This message is on-the-record unless we agree otherwise>

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