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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: can't write with consistency level of one after some nodes fail
Date Thu, 29 Oct 2009 21:39:36 GMT
I've seen that bug too.  I think we introduced a regression with CASSANDRA-492.

On Thu, Oct 29, 2009 at 3:37 PM, Edmond Lau <edmond@ooyala.com> wrote:
> I've updated to trunk, and I'm still hitting the same issue but it's
> manifesting itself differently.  Again, I'm running with a freshly
> started 3-node cluster with a replication factor of 2.  I then take
> down two nodes.
>
> If I write with a consistency level of ONE on any key, I get an
> InvalidRequestException:
>
> ERROR [pool-1-thread-45] 2009-10-29 21:27:10,120 StorageProxy.java
> (line 183) error writing key 1
> InvalidRequestException(why:Cannot block for less than one replica)
>        at org.apache.cassandra.service.QuorumResponseHandler.<init>(QuorumResponseHandler.java:52)
>        at org.apache.cassandra.locator.AbstractReplicationStrategy.getResponseHandler(AbstractReplicationStrategy.java:64)
>        at org.apache.cassandra.service.StorageService.getResponseHandler(StorageService.java:869)
>        at org.apache.cassandra.service.StorageProxy.insertBlocking(StorageProxy.java:162)
>        at org.apache.cassandra.service.CassandraServer.doInsert(CassandraServer.java:473)
>        at org.apache.cassandra.service.CassandraServer.insert(CassandraServer.java:424)
>        at org.apache.cassandra.service.Cassandra$Processor$insert.process(Cassandra.java:819)
>        at org.apache.cassandra.service.Cassandra$Processor.process(Cassandra.java:624)
>        at org.apache.thrift.server.TThreadPoolServer$WorkerProcess.run(TThreadPoolServer.java:253)
>        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
>        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
>        at java.lang.Thread.run(Thread.java:619)
>
> Oddly, a write with a consistency level of QUORUM succeeds for certain
> keys (but fails with others) even though I only have one live node.
>
> Edmond
>
> On Thu, Oct 29, 2009 at 1:38 PM, Edmond Lau <edmond@ooyala.com> wrote:
>>
>> On Thu, Oct 29, 2009 at 1:20 PM, Jonathan Ellis <jbellis@gmail.com> wrote:
>>>
>>> On Thu, Oct 29, 2009 at 1:18 PM, Edmond Lau <edmond@ooyala.com> wrote:
>>> > I have a freshly started 3-node cluster with a replication factor of
>>> > 2.  If I take down two nodes, I can no longer do any writes, even with
>>> > a consistency level of one.  I tried on a variety of keys to ensure
>>> > that I'd get at least one where the live node was responsible for one
>>> > of the replicas.  I have not yet tried on trunk.  On cassandra 0.4.1,
>>> > I get an UnavailableException.
>>>
>>> This sounds like the bug we fixed in CASSANDRA-496 on trunk.
>>
>> Excellent - thanks.  Time to start using trunk.
>>
>>>
>>> > Along the same lines, how does Cassandra handle network partitioning
>>> > where 2 writes for the same keys hit 2 different partitions, neither
>>> > of which are able to form a quorum?  Dynamo maintained version vectors
>>> > and put the burden on the client to resolve conflicts, but there's no
>>> > similar interface in the thrift api.
>>>
>>> If you use QUORUM or ALL consistency, neither write will succeed.  If
>>> you use ONE, both will, and the one with the higher timestamp will
>>> "win" when the partition heals.
>>
>> Got it.
>>
>>>
>>> -Jonathan
>>
>> Edmond
>

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