Re: One-element vs two-element design

[Petri Helenius <pete () he iki fi>]

Eric Kuhnke wrote:

> Last year, a Boeing in flight over the middle of the pacific ocean had 
> its entire glass cockpit system go dark.  After frantic conversation 
> with the air traffic controllers a decision was made to toggle the 
> circuit breakers for the TRIPLE-REDUNDANT computer system onboard, 
> which brought back the displays.  Even with a 2+1 setup, things can 
> still go wrong...
Most, if not all, redundant systems have a single instance of  
synchronization protocol.
One significant vendor of packet forwarding gear was known for hanging 
the secondary
RP almost every time when the primary failed. The hang was usually 
associated with
chatter failing with the failed card :-)

Pete