[erlang-questions] Mnesia vs When Databases Lie: Consistency vs Availability in Distributed Systems

PatrickErj <>
Mon Dec 17 14:58:19 CET 2007


That option costs min. one million dollars and the Facebook case is just
lame. You will need 1Gbps link that is redundant and costs min. 40$/Mbps
i.e. 45K$US/month let alone duplicate servers. Globally dis pared system is
ok for doc's but not ok for HA/HPC DB. Also Amazon AWS does not cut well for
"stock exchange" because you are talking about 10< microseconds and AWS is
talking about 10< miliseconds in db transaction time, that is why Google has
mapreduce.





Joel Reymont wrote:
> 
> How does Erlang change or improve this situation?
> 
> http://tinyurl.com/2745ha
> 
> I can't imagine a fragmented Mnesia table would help here, not when  
> one chunk lives in Europe and another in the US.
> 
> I also imagine there would be significant costs in Transatlantic  
> replication (in terms of transaction time, not dollars) if a regular  
> distributed Mnesia table is used.
> 
> I want to dig deep into Mnesia for the corresponding chapter of my  
> book. I plan to try to figure out and write up the distributed commit  
> protocol, for example.
> 
> I think I'll also try to set up exactly the scenario that the above  
> article describes (two machines, multiple Mnesia nodes) and simulate  
> denial of service attacks, tripping over power cords, etc.
> 
> I want to know exactly how much network bandwidth is taken by  
> replication among other things and what exactly happens when I bring  
> up a Mnesia node that went down. There was a discussion of this  
> recently but nothing beats a step by step explanation.
> 
> 	Thanks, Joel
> 
> 
> --
> http://wagerlabs.com
> 
> 
> 
> 
> 
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> 
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> 
> 

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