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From Benjamin Reed <br...@yahoo-inc.com>
Subject RE: What happens when a server loses all its state?
Date Thu, 18 Dec 2008 22:59:37 GMT
I have opened ZOOKEEPER-261 for this issue. it shouldn't be too hard to fix and it would be
nice to target for 3.1.

ben

-----Original Message-----
From: Thomas.Johnson@Sun.COM [mailto:Thomas.Johnson@Sun.COM] 
Sent: Wednesday, December 17, 2008 2:52 PM
To: zookeeper-user@hadoop.apache.org
Subject: Re: What happens when a server loses all its state?

Thanks for all the responses.
Benjamin Reed wrote:
> Thomas, 
>
> in the scenario you give you have two simultaneous failures with 3 nodes, so it will
not recover correctly. A is failed because it is not up. B has failed because it lost all
its data.
>
> it would be good for ZooKeeper to not come up in that scenario. perhaps what we need
is something similar to your safe state proposal. basically a server that has forgotten everything
should not be allowed to vote in the leader election. that would avoid your scenario. we just
need to put a flag file in the data directory to say that the data is valid and thus can vote.
>
> ben
> ________________________________________
>   
Would this feature be something you'd consider implementing in the short 
to medium term?

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