More stuff from the Sun rescue

Chuck Guzis cclist at sydex.com
Tue Oct 30 10:35:15 CDT 2007


On 30 Oct 2007 at 10:19, Sridhar Ayengar wrote:

> Refresh my memory how those worked?  Two processors in lock-step?  Three 
> processors in a voting quorum?

Nothing that simple.  Special software and hardware.  As was driven 
home to me by a Tandem engineer who was also a good friend, the term 
of art used by Tandem is "Nonstop" not "Fault tolerant".  A world of 
difference between them.  For a very good analysis, check out the 
paper "Why Do Computers Stop and What Can Be Done About It?" by 
Tandem's Jim Gray.  It should be somewhere on the web, given its 
importance.  It describes in very eloquent terms, the Tandem 
philosophy.

Cheers,
Chuck




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