cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From aaron morton <aa...@thelastpickle.com>
Subject Re: consistency level question
Date Mon, 19 Mar 2012 09:49:12 GMT
Some information on node failures, consistency levels and availability http://thelastpickle.com/2011/06/13/Down-For-Me/

Cheers


-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com

On 19/03/2012, at 1:08 PM, Watanabe Maki wrote:

> 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 
>>> 
>>> 
>>> 
>> 


Mime
View raw message