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HDFS accessing issue in a Namenode HA confiugration

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HDFS accessing issue in a Namenode HA confiugration

Contributor

I have some problems accessing HDFS after enabling Namenode HA. I belive this is by design but want to know if there are any workarounds.

 

Here is my setup:

Before enabling NN HA:

 

Namenode hostname ==> node01.mydomain.com

Namenode CNMAE on DNS ==> hdfs.mydomain.com ( this points to node01.mydomain.com)

 

To access the namenode from outside of the cluster, people uses commnad like below:

$ hadoop fs -ls hdfs://hdfs.mydomain.com

 

Some application also hard coded the CNAME when accssing from inside the cluster.

 

After eanbleing NN HA:

 

Active Namenode hostname==> node01.mydomain.com

Backup Namenode hostname==>node02.mydomain.com

dfs.nameservices==> mycluster

Namenode CNMAE on DNS ==> hdfs.mydomain.com ( this points to node01.mydomain.com)

 

People can still access HDFS by using  hdfs:\\hdfs.mydomain.com. But the problme is that it won't work if the namenode failed over to node002.mydomain.com, it will complain-- "the opertaion is not supported in standby mode". This is expected to me as the CNAME still points to node001.mydomain.com which runs in standby mode.

 

I undestand people can always access namnode regardless which node is active by using hdfs:\\mycluster, but this won't work if the hdfs client is outside the cluster and the application which use hardcoded CNAME won't work either.

 

Does anyone have this problem too? How do you workaround it?

 

 

 

 

 

3 REPLIES 3

Re: HDFS accessing issue in a Namenode HA confiugration

Contributor

Does anyone have a comment on this topic?

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Re: HDFS accessing issue in a Namenode HA confiugration

Champion
Can you give us more about the error that user is getting or any log stack trace with zookeeper .
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Re: HDFS accessing issue in a Namenode HA confiugration

Contributor

There is no error. When accessing hdfs://hdfs.mydomain.com, the command output just says "the opertion is not supported in standby mode".

 

I think this is by design, but wondering if anyone has a workaround.

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