question Re: NameNode HA - HBASE has to be stopped in Support Questions

NameNode HA - HBASE has to be stopped

sreeviswa_athic — Thu, 09 Mar 2017 09:55:17 GMT

While configuring NameNode HA its recommended to stop HBASE prior, curious to know why HBASE has to stopped for NameNode High Availability.

Re: NameNode HA - HBASE has to be stopped

pminovic — Thu, 09 Mar 2017 10:23:52 GMT

Note that you need at least to restart HBase after configuring NN HA to give HBase a chance to pick up on the new configuration, instead of using only one NN. I guess strictly speaking you can keep HBase running, and restart it once NN HA is over, but it's better to stop it to avoid any inconsistencies and other troubles.

Re: NameNode HA - HBASE has to be stopped

aervits — Thu, 09 Mar 2017 20:43:49 GMT

When you enable HA, you essentially are changing name of the namenode with nameservers, you have to update hbase.rootdir property to reflect the nameservices ID and hence the stop.

  <property>
    <name>hbase.rootdir</name>
    <value>hdfs://namenode.example.org:8020/hbase</value>
  </property>

Re: NameNode HA - HBASE has to be stopped

namaheshwari — Fri, 10 Mar 2017 02:41:01 GMT

HBase Distributed modes require an instance of HDFS. HBase depends on HDFS (Namenode, Datanodes) to perform operations like adding a file etc. So, if you a running cluster where HBase is also installed and you are upgrading HDFS to be HA i.e to Namenode-HA you should stop HBase service.

Also, as Artem mentioned above after upgrading the Namenode to HA, change the distributed file system URI in hbase-site.xml to the name specified in the dfs.nameservices property in hdfs-site.xml.

For example, suppose the HDFS HA property dfs.nameservices is set to mycluster in hdfs-site.xml. Specify that same value as below in hbase-site.xml's hbase.rootdir value:

<!-- Configure HBase to use the HA NameNode nameservice -->
<property>
  <name>hbase.rootdir</name>
  <value>hdfs://mycluster/hbase</value>
</property>

Re: NameNode HA - HBASE has to be stopped

sreeviswa_athic — Fri, 10 Mar 2017 02:59:42 GMT

thank you, makes sense

Re: NameNode HA - HBASE has to be stopped

namaheshwari — Fri, 10 Mar 2017 03:06:20 GMT

Thanks @Viswa. Can you please upvote and accept the answer as well.

Re: NameNode HA - HBASE has to be stopped

sreeviswa_athic — Fri, 10 Mar 2017 03:11:03 GMT

Sure will do, can you please also let me know what kind of preliminary checks I can do after configuring NameHA

Re: NameNode HA - HBASE has to be stopped

namaheshwari — Fri, 10 Mar 2017 03:20:30 GMT

These checks should suffice the health of HDFS:

https://docs.hortonworks.com/HDPDocuments/HDP2/HDP-2.5.3/bk_command-line-upgrade/content/verify-hdfs-24.html

Although the document is for manual upgrade, but the health checks should be good enough

Re: NameNode HA - HBASE has to be stopped

namaheshwari — Sat, 11 Mar 2017 05:30:08 GMT

@Viswa - Can we close this now?