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From Watanabe Maki <watanabe.m...@gmail.com>
Subject Re: consistency level question
Date Mon, 19 Mar 2012 00:08:15 GMT
Yes, read and write won't fail with single node failure.
But your read may return old data.

maki

On 2012/03/19, at 1:08, Caleb Rackliffe <caleb@steelhouse.com> wrote:

> That sounds right to me :)
> 
> Caleb Rackliffe | Software Developer	
> M 949.981.0159 | caleb@steelhouse.com
> <EB2FF764-478C-4966-9B0A-E7B76D6AD7DC[18].png>
> 
> From: Tamar Fraenkel <tamar@tok-media.com>
> Reply-To: "user@cassandra.apache.org" <user@cassandra.apache.org>
> Date: Sun, 18 Mar 2012 04:20:58 -0400
> To: "user@cassandra.apache.org" <user@cassandra.apache.org>
> Subject: Re: consistency level question
> 
> Thanks!
> I updated replication factor to 2, and now when I took one node down all continued running
(I did see Hector complaining on the node being down), but things were saved to db and read
from it.
> 
> Just so I understand, now, having replication factor of 2, if I have 2 out of 3 nodes
running all my read and writes with CL=1 should work, right?
> 
> 
> Tamar Fraenkel 
> Senior Software Engineer, TOK Media 
> 
> <tokLogo.png>
> 
> tamar@tok-media.com
> Tel:   +972 2 6409736 
> Mob:  +972 54 8356490 
> Fax:   +972 2 5612956 
> 
> 
> 
> 
> 
> On Sun, Mar 18, 2012 at 9:57 AM, Watanabe Maki <watanabe.maki@gmail.com> wrote:
> Because your RF is 1, so you need all nodes up.
> 
> maki
> 
> 
> On 2012/03/18, at 16:15, Tamar Fraenkel <tamar@tok-media.com> wrote:
> 
>> Hi!
>> I have a 3 node cassandra cluster.
>> I use Hector API.
>> 
>> I give hecotr one of the node's IP address
>> I call setAutoDiscoverHosts(true) and setRunAutoDiscoveryAtStartup(true).
>> 
>> The describe on one node returns:
>> 
>> Replication Strategy: org.apache.cassandra.locator.SimpleStrategy
>>   Durable Writes: true
>>     Options: [replication_factor:1]
>> 
>> The odd thing is that when I take one of the nodes down, expecting all to continue
running smoothly, I get exceptions of the format seen bellow, and no read or write succeeds.
When I bring the node back up, exceptions stop and read and write resumes.
>> 
>> Any idea or explanation why this is the case?
>> Thanks!
>> 
>> 
>> me.prettyprint.hector.api.exceptions.HUnavailableException: : May not be enough replicas
present to handle consistency level.
>>         at me.prettyprint.cassandra.service.ExceptionsTranslatorImpl.translate(ExceptionsTranslatorImpl.java:66)
>>         at me.prettyprint.cassandra.service.KeyspaceServiceImpl$7.execute(KeyspaceServiceImpl.java:285)
>>         at me.prettyprint.cassandra.service.KeyspaceServiceImpl$7.execute(KeyspaceServiceImpl.java:268)
>>         at me.prettyprint.cassandra.service.Operation.executeAndSetResult(Operation.java:103)
>>         at me.prettyprint.cassandra.connection.HConnectionManager.operateWithFailover(HConnectionManager.java:246)
>>         at me.prettyprint.cassandra.service.KeyspaceServiceImpl.operateWithFailover(KeyspaceServiceImpl.java:131)
>>         at me.prettyprint.cassandra.service.KeyspaceServiceImpl.getSlice(KeyspaceServiceImpl.java:289)
>>         at me.prettyprint.cassandra.model.thrift.ThriftSliceQuery$1.doInKeyspace(ThriftSliceQuery.java:53)
>>         at me.prettyprint.cassandra.model.thrift.ThriftSliceQuery$1.doInKeyspace(ThriftSliceQuery.java:49)
>>         at me.prettyprint.cassandra.model.KeyspaceOperationCallback.doInKeyspaceAndMeasure(KeyspaceOperationCallback.java:20)
>>         at me.prettyprint.cassandra.model.ExecutingKeyspace.doExecute(ExecutingKeyspace.java:85)
>>         at me.prettyprint.cassandra.model.thrift.ThriftSliceQuery.execute(ThriftSliceQuery.java:48)
>>         at me.prettyprint.cassandra.service.ColumnSliceIterator.hasNext(ColumnSliceIterator.java:60)
>>         at 
>> 
>> 
>> Tamar Fraenkel 
>> Senior Software Engineer, TOK Media 
>> 
>> <tokLogo.png>
>> 
>> 
>> tamar@tok-media.com
>> Tel:   +972 2 6409736 
>> Mob:  +972 54 8356490 
>> Fax:   +972 2 5612956 
>> 
>> 
>> 
> 

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