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From Shalom Sagges <shal...@liveperson.com>
Subject Re: WriteTimeoutException When only One Node is Down
Date Sun, 15 Jan 2017 10:27:56 GMT
Hi Yuji,

Thanks for your reply.
That's what I don't understand. Since the writes are in LOCAL_QUORUM, even
if a node fails, there should be enough replica to satisfy the request,
shouldn't it?
Otherwise, the whole idea behind no single point of failure is only
partially true? Or is there something I'm missing...

Thanks!


Shalom Sagges
DBA
T: +972-74-700-4035
<http://www.linkedin.com/company/164748> <http://twitter.com/liveperson>
<http://www.facebook.com/LivePersonInc> We Create Meaningful Connections
<https://liveperson.docsend.com/view/8iiswfp>


On Fri, Jan 13, 2017 at 4:15 AM, Yuji Ito <yuji@imagine-orb.com> wrote:

> Hi Shalom,
>
> I also got WriteTimeoutException in my destructive test like your test.
>
> When did you drop a node?
> A coordinator node sends a write request to all replicas.
> When one of nodes was down while the request is executed, sometimes
> WriteTimeOutException happens.
>
> cf. http://www.datastax.com/dev/blog/cassandra-error-handling-done-right
>
> Thanks,
> Yuji
>
>
>
> On Thu, Jan 12, 2017 at 4:26 PM, Shalom Sagges <shaloms@liveperson.com>
> wrote:
>
>> Hi Everyone,
>>
>> I'm using C* v3.0.9 for a cluster of 3 DCs with RF 3 in each DC. All
>> read/write queries are set to consistency LOCAL_QUORUM.
>> The relevant keyspace is built as follows:
>>
>> *CREATE KEYSPACE mykeyspace WITH replication = {'class':
>> 'NetworkTopologyStrategy', 'DC1': '3', 'DC2': '3', 'DC3': '3'}  AND
>> durable_writes = true;*
>>
>> I use* Datastax driver 3.0.1*
>>
>>
>> When I performed a resiliency test for the application, each time I
>> dropped one node, the client got the following error:
>>
>>
>> com.datastax.driver.core.exceptions.WriteTimeoutException: Cassandra
>> timeout during write query at consistency TWO (2 replica were required but
>> only 1 acknowledged the write)
>> at com.datastax.driver.core.exceptions.WriteTimeoutException.
>> copy(WriteTimeoutException.java:73)
>> at com.datastax.driver.core.exceptions.WriteTimeoutException.
>> copy(WriteTimeoutException.java:26)
>> at com.datastax.driver.core.DriverThrowables.propagateCause(Dri
>> verThrowables.java:37)
>> at com.datastax.driver.core.DefaultResultSetFuture.getUninterru
>> ptibly(DefaultResultSetFuture.java:245)
>> at com.datastax.driver.core.AbstractSession.execute(AbstractSes
>> sion.java:63)
>> at humanclick.ldap.commImpl.siteData.CassandraSiteDataDaoSpring
>> .updateJprunDomains(CassandraSiteDataDaoSpring.java:121)
>> at humanclick.ldap.commImpl.siteData.CassandraSiteDataDaoSpring
>> .createOrUpdate(CassandraSiteDataDaoSpring.java:97)
>> at humanclick.ldapAdapter.dataUpdater.impl.SiteDataToLdapUpdate
>> r.update(SiteDataToLdapUpdater.java:280)
>>
>>
>> After a few seconds the error no longer recurs. I have no idea why
>> there's a timeout since there are additional replicas that satisfy the
>> consistency level, and I'm more baffled when the error showed *"Cassandra
>> timeout during write query at consistency TWO (2 replica were required but
>> only 1 acknowledged the write)"*
>>
>> Any ideas?  I'm quite at a loss here.
>>
>> Thanks!
>>
>>
>>
>> Shalom Sagges
>> DBA
>> T: +972-74-700-4035 <+972%2074-700-4035>
>> <http://www.linkedin.com/company/164748> <http://twitter.com/liveperson>
>> <http://www.facebook.com/LivePersonInc> We Create Meaningful Connections
>>
>>
>>
>> This message may contain confidential and/or privileged information.
>> If you are not the addressee or authorized to receive this on behalf of
>> the addressee you must not use, copy, disclose or take action based on this
>> message or any information herein.
>> If you have received this message in error, please advise the sender
>> immediately by reply email and delete this message. Thank you.
>>
>
>

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