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From Kirk True <k...@mustardgrain.com>
Subject Re: Replication factor - Consistency Questions
Date Thu, 19 Jul 2012 22:24:19 GMT
But isn't QUORUM on a 2-node cluster still 2 nodes?

On 07/17/2012 11:50 PM, Jason Tang wrote:
> Yes, for ALL, it is not good for HA, and because we meet problem when 
> use QUORAM, and current solution is switch Write:QUORAM / Read:QUORAM 
> when got "UnavailableException" exception.
>
> 2012/7/18 Jay Parashar <jparashar@itscape.com 
> <mailto:jparashar@itscape.com>>
>
>     Thanks..but write ALL will fail for any downed nodes. I am
>     thinking of QUORAM.
>
>     *From:*Jason Tang [mailto:ares.tang@gmail.com
>     <mailto:ares.tang@gmail.com>]
>     *Sent:* Tuesday, July 17, 2012 8:24 PM
>     *To:* user@cassandra.apache.org <mailto:user@cassandra.apache.org>
>     *Subject:* Re: Replication factor - Consistency Questions
>
>     Hi
>
>     I am starting using Cassandra for not a long time, and also have
>     problems in consistency.
>
>     Here is some thinking.
>
>     If you have Write:Any / Read:One, it will have consistency
>     problem, and if you want to repair, check your schema, and check
>     the parameter "Read repair chance: "
>
>     http://wiki.apache.org/cassandra/StorageConfiguration
>
>     And if you want to get consistency result, my suggestion is to
>     have Write:ALL / Read:One, since for Cassandra, write is more
>     faster then read.
>
>     For performance impact, you need to test your traffic, and if your
>     memory can not cache all your data, or your network is not fast
>     enough, then yes, it will impact to write one more node.
>
>     BRs
>
>     2012/7/18 Jay Parashar <jparashar@itscape.com
>     <mailto:jparashar@itscape.com>>
>
>     Hello all,
>
>     There is a lot of material on Replication factor and Consistency
>     level but I
>     am a little confused by what is happening on my setup. (Cassandra
>     1.1.2). I
>     would appreciate any answers.
>
>     My Setup: A cluster of 2 nodes evenly balanced. My RF =2,
>     Consistency Level;
>     Write = ANY and Read = 1
>
>     I know that my consistency is Weak but since my RF = 2, I thought
>     data would
>     be just duplicated in both the nodes but sometimes, querying does
>     not give
>     me the correct (or gives partial) results. In other times, it
>     gives me the
>     right results
>     Is the Read Repair going on after the first query? But as RF = 2,
>     data is
>     duplicated then why the repair?
>     Note: My query is done a while after the Writes so data should
>     have been in
>     both the nodes. Or is this not the case (flushing not happening etc)?
>
>     I am thinking of making the Write as 1 and Read as QUORAM so R + W
>     > RF (1 +
>     2 > 2) to give strong consistency. Will that affect performance a lot
>     (generally speaking)?
>
>     Thanks in advance
>     Regards
>
>     Jay
>
>


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