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From: Harsh J <harsh@cloudera.com>
Date: Wed, 30 Apr 2014 17:49:54 +0530
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Subject: Re: For QJM HA solution, after failover, application must update
 NameNode IP?
To: "<user@hadoop.apache.org>" <user@hadoop.apache.org>
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Hi Sam,

Bryan meant the last config bit:

 <property>
      <name>dfs.client.failover.proxy.provider.gilbert-prod</name>
      <value>org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider</value>
  </property>

This is the class the client will use to perform the failover (i.e.
active NN discovery).

On Tue, Apr 29, 2014 at 7:37 PM, sam liu <samliuhadoop@gmail.com> wrote:
> Hi Bryan,
>
> Thanks for your detailed response!
>
> - 'you use a logical name for your "group of namenodes"': In your case, it
> should be 'MYCLUSTER'
>
> - 'provide a means for the client to handle connecting to the currently
> active one': Could you pls give an example?
>
>
>
>
> 2014-04-29 21:57 GMT+08:00 Bryan Beaudreault <bbeaudreault@hubspot.com>:
>
>> If you are using the QJM HA solution, the IP addresses of the namenodes
>> should not change.  Instead your clients should be connecting using the
>> proper HA configurations.  That is, you use a logical name for your "group
>> of namenodes", and provide a means for the client to handle connecting to
>> the currently active one.
>>
>> Example:
>>
>> <property>
>>       <name>dfs.nameservices</name>
>>       <value>MYCLUSTER</value>
>>   </property>
>>
>>   <property>
>>       <name>dfs.ha.namenodes.MYCLUSTER</name>
>>       <value>nn1,nn2</value>
>>   </property>
>>
>>   <property>
>>       <name>dfs.namenode.rpc-address.MYCLUSTER.nn1</name>
>>       <value>dnsOfNameNode1:8020</value>
>>   </property>
>>   <property>
>>       <name>dfs.namenode.http-address.MYCLUSTER.nn1</name>
>>       <value> dnsOfNameNode1:50070</value>
>>   </property>
>>
>>   <property>
>>       <name>dfs.namenode.rpc-address.MYCLUSTER.nn2</name>
>>       <value> dnsOfNameNode2:8020</value>
>>   </property>
>>   <property>
>>       <name>dfs.namenode.http-address.MYCLUSTER.nn2</name>
>>       <value> dnsOfNameNode2:50070</value>
>>   </property>
>>
>>   <property>
>>       <name>dfs.client.failover.proxy.provider.gilbert-prod</name>
>>
>> <value>org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider</value>
>>   </property>
>>
>>
>> On Tue, Apr 29, 2014 at 9:07 AM, sam liu <samliuhadoop@gmail.com> wrote:
>>>
>>> Hi Experts,
>>>
>>> For example, at the beginning, the application will access NameNode using
>>> IP of active NameNode(IP: 9.123.22.1).  However, after failover, the IP of
>>> active NameNode is changed to 9.123.22.2 which is the IP of previous standby
>>> NameNode. In this case, application must update NameNode IP?
>>>
>>> Thanks!
>>
>>
>



-- 
Harsh J