incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Yan Chunlu <springri...@gmail.com>
Subject Re: increased RF and repair, not working?
Date Fri, 27 Jul 2012 15:56:58 GMT
I think Dave is right,  I have read this article again:
http://thelastpickle.com/2011/07/04/Cassandra-Query-Plans/

I have data on two nodes, and "QUORUM read" means it need read from both
two nodes.

I guess I need to increase the RF to 3, to make the system can tolerance
one node failure.

thanks for all of the kind help!
On Fri, Jul 27, 2012 at 8:08 PM, Riyad Kalla <rkalla@gmail.com> wrote:

> Dave, per my understanding of Yan's description he has 3 nodes and took
> one down manually to test; that should have worked, no?
>
>
> On Thu, Jul 26, 2012 at 11:00 PM, Dave Brosius <dbrosius@mebigfatguy.com>wrote:
>
>>  Quorum is defined as
>>
>> (replication_factor / 2) + 1
>> therefore quorum when rf = 2 is 2! so in your case, both nodes must be up.
>>
>> Really, using Quorum only starts making sense as a 'quorum' when RF=3
>>
>>
>>
>>
>>
>>
>> On 07/26/2012 10:38 PM, Yan Chunlu wrote:
>>
>> I am using Cassandra 1.0.2, have a 3 nodes cluster. the consistency level
>> of read & write are  both QUORUM.
>>
>>  At first the RF=1, and I figured that one node down will cause the
>> cluster unusable. so I changed RF to 2, and run nodetool repair on every
>> node(actually I did it twice).
>>
>>  After the operation I think my data should be in at least two nodes,
>> and it would be okay if one of them is down.
>>
>> But when I tried to simulate the failure, by disablegossip of one node,
>> and the cluster knows this node is down. then access data from the cluster,
>> it returned  "MaximumRetryException"(pycassa).   as my experiences this is
>> caused by "UnavailableException", which is means the data it is requesting
>> is on a node which is down.
>>
>>  so I wonder my data might not be replicated right, what should I do?
>> thanks for the help!
>>
>>  here is the keyspace info:
>>
>>  *
>> *
>>  *Keyspace: comments:*
>> *  Replication Strategy: org.apache.cassandra.locator.SimpleStrategy*
>> *  Durable Writes: true*
>> *    Options: [replication_factor:2]*
>>
>>
>>
>>  the scheme version is okay:
>>
>>  *[default@unknown] describe cluster;*
>> *Cluster Information:*
>> *   Snitch: org.apache.cassandra.locator.SimpleSnitch*
>> *   Partitioner: org.apache.cassandra.dht.RandomPartitioner*
>> *   Schema versions: *
>> * f67d0d50-b923-11e1-0000-4f7cf9240aef: [192.168.1.129, 192.168.1.40,
>> 192.168.1.50]*
>>
>>
>>
>>  the loads are as below:
>>
>>  *nodetool -h localhost ring*
>> *Address         DC          Rack        Status State   Load
>>  Owns    Token                                       *
>> *
>>        113427455640312821154458202477256070484     *
>> *192.168.1.50    datacenter1 rack1       Up     Normal  28.77 GB
>>  33.33%  0                                           *
>> *192.168.1.40    datacenter1 rack1       Up     Normal  26.67 GB
>>  33.33%  56713727820156410577229101238628035242      *
>> *192.168.1.129   datacenter1 rack1       Up     Normal  33.25 GB
>>  33.33%  113427455640312821154458202477256070484    *
>>
>>
>>
>

Mime
View raw message