hadoop-hdfs-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Chris Nauroth <cnaur...@hortonworks.com>
Subject Re: check decommission status
Date Thu, 29 Oct 2015 15:52:42 GMT
Hello Surbhi,

There is no public, stable Java API for this.  If you look at the
implementation of "hdfs dfsadmin -report", it involves downcasting from
the base FileSystem class to the concrete DistributedFileSystem, and then
calling DistributedFileSystem#getDataNodeStats.

https://github.com/apache/hadoop/blob/trunk/hadoop-hdfs-project/hadoop-hdfs
/src/main/java/org/apache/hadoop/hdfs/tools/DFSAdmin.java#L523


You could potentially mimic this code from DFSAdmin, but please keep in
mind that you'd be calling internal APIs that do not come with a strong
stability guarantee.  We might evolve those APIs across releases in ways
that would break your application after upgrading to a later version.

Another more stable approach would be to parse the shell output of "hdfs
dfsadmin -report".  We offer a backward compatibility guarantee on shell
output.

A third approach is to call the NameNode's HTTP server to get a JSON dump
of NameNode JMX metrics.  The NameNodeInfo MBean includes a "DecomNodes"
field with information about decommissioning nodes.  Here is a sample curl
call, assuming a NameNode running on localhost with its HTTP server
listening on port 50070.

curl 
'http://127.0.0.1:50070/jmx?qry=Hadoop:service=NameNode,name=NameNodeInfo'


More details on our compatibility policy are listed here in case you're
interested.

https://hadoop.apache.org/docs/current/hadoop-project-dist/hadoop-common/Co
mpatibility.html


--Chris Nauroth




On 10/29/15, 8:40 AM, "Surbhi Gupta" <surbhi.gupta01@gmail.com> wrote:

>You can try nodetool netstats . If you find streaming happening from the
>decommission node to other node and vise versa then decommission is still
>going on .
>
>Sent from my iPhone
>
>> On Oct 28, 2015, at 10:54 PM, ram kumar <ramkumarrock3@gmail.com> wrote:
>> 
>> Hi,
>> 
>> Is there a java api to get decommission status for a particular data
>>node?
>> 
>> Thanks.
>


Mime
View raw message