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From Viktor Jevdokimov <Viktor.Jevdoki...@adform.com>
Subject RE: Quorum: killing 1 out of 3 server kills the cluster (?)
Date Thu, 09 Dec 2010 16:13:03 GMT
With 3 nodes and RF=2 you have 3 key ranges: N1+N2, N2+N3 and N3+N1.
Killing N1 you've got only 1 alive range N2+N3 and 2/3 of the range is down for Quorum, which
is actually all, so N1+N2 and N3+N1 fails.

-----Original Message-----
From: Timo Nentwig [mailto:timo.nentwig@toptarif.de] 
Sent: Thursday, December 09, 2010 6:01 PM
To: user@cassandra.apache.org
Subject: Re: Quorum: killing 1 out of 3 server kills the cluster (?)


On Dec 9, 2010, at 16:50, Daniel Lundin wrote:

> Quorum is really only useful when RF > 2, since the for a quorum to
> succeed RF/2+1 replicas must be available.

2/2+1==2 and I killed 1 of 3, so... don't get it.

> This means for RF = 2, consistency levels QUORUM and ALL yield the same result.
> 
> /d
> 
> On Thu, Dec 9, 2010 at 4:40 PM, Timo Nentwig <timo.nentwig@toptarif.de> wrote:
>> Hi!
>> 
>> I've 3 servers running (0.7rc1) with a replication_factor of 2 and use quorum for
writes. But when I shut down one of them UnavailableExceptions are thrown. Why is that? Isn't
that the sense of quorum and a fault-tolerant DB that it continues with the remaining 2 nodes
and redistributes the data to the broken one as soons as its up again?
>> 
>> What may I be doing wrong?
>> 
>> thx
>> tcn




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