Namenode backup help

[#1]

Hello -

I am trying to run the hdfs dfsadmin -fetchImage command to get a back up of our Namenode.

It is failing similar to this thread ->

http://community.cloudera.com/t5/CDH-Manual-Installation/Backing-up-Namenode-FSImage/m-p/27268#M727

In that post, there is the suggestion below...about adding users to the dfs.cluster.adminstrators property (see snippet below). 

We are on CM 5.11 and I am not finding this property.  Does anyone know how to set it?  Or, do i have to just update some config ini/xml file?

Thanks...d 

=== from link ===

In clusters managed by Cloudera Manager 5.x, the property is set to "hdfs" by default. So if this command is run as the hdfs user on any node on the cluster, the command will succeed.

You can try setting dfs.cluster.administrators to the list of users and groups who are allowed to perform this operation and then try again. It will require a restart of the Namenode(s) to take effect.

<property>
<name>dfs.cluster.administrators</name>
<value>user1,user2,user3 group1,group2,group3</value>
</property>

[#2 · Accepted solution]

You should place that config XML snippet under HDFS - Configuration -
'NameNode Advanced Configuration Snippet (Safety Valve) for hdfs-site.xml'
field.

For more on what the 'Advanced Configuration Snippet' / 'Safety Valve'
fields are:
https://www.cloudera.com/documentation/enterprise/latest/topics/cm_mc_config_snippet.html#xd_583c10b...

[#3]

Thanks so much for the help.

That worked.  I was able to get the backup of the fsimage.