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From Sudhir Vallamkondu <Sudhir.Vallamko...@icrossing.com>
Subject Re: Help: 1) Hadoop processes still are running after we stopped hadoop.2) How to exclude a dead node?
Date Wed, 08 Dec 2010 15:41:09 GMT

Reference: I couldn't find a apache hadoop page describing this but see
below link 

On 12/7/10 11:59 PM, "common-user-digest-help@hadoop.apache.org"
<common-user-digest-help@hadoop.apache.org> wrote:

> From: li ping <li.j2ee@gmail.com>
> Date: Wed, 8 Dec 2010 14:17:40 +0800
> To: <common-user@hadoop.apache.org>
> Subject: Re: Help: 1) Hadoop processes still are running after we stopped >
> hadoop.2) How to exclude a dead node?
> I am not sure I have fully understand your post.
> You mean the conf/slaves only be used for stop/start script to start or stop
> the datanode/tasktracker?
> And the conf/master only contains the information about the secondary
> namenode?
> Thanks
> On Wed, Dec 8, 2010 at 1:44 PM, Sudhir Vallamkondu <
> Sudhir.Vallamkondu@icrossing.com> wrote:
>> There is a proper decommissioning process to remove dead nodes. See the FAQ
>> link here:
>> http://wiki.apache.org/hadoop/FAQ#I_want_to_make_a_large_cluster_smaller_by_
>> taking_out_a_bunch_of_nodes_simultaneously._How_can_this_be_done.3F
>> For a fact $HADOOP_HOME/conf/slaves is not used by the name node to keep
>> track of datanodes/tasktracker. It is merely used by the stop/start hadoop
>> scripts to know which nodes to start datanode / tasktracker services.
>> Similarly there is confusion regarding understanding the
>> $HADOOP_HOME/conf/master file. That file contains the details of the
>> machine
>> where secondary name node is running, not the name node/job tracker.
>> With regards to not all java/hadoop processes getting killed, this may be
>> happening due to hadoop loosing track of pid files. By default the pid
>> files
>> are configured to be created in the /tmp directory. If these pid files get
>> deleted then stop/start scripts cannot detect running hadoop processes. I
>> suggest changing location of pid files to a persistent location like
>> /var/hadoop/. The $HADOOP_HOME/conf/hadoop-env.sh file has details on
>> configuring the PID location
>> - Sudhir
>> On 12/7/10 5:07 PM, "common-user-digest-help@hadoop.apache.org"
>> <common-user-digest-help@hadoop.apache.org> wrote:
>>> From: Tali K <ncherryus@hotmail.com>
>>> Date: Tue, 7 Dec 2010 10:40:16 -0800
>>> To: <core-user@hadoop.apache.org>
>>> Subject: Help: 1) Hadoop processes still are running after we stopped
>>> hadoop.2)  How to exclude a dead node?
>>> 1)When I stopped hadoop, we checked all the nodes and found that 2 or 3
>>> java/hadoop processes were still running on each node.  So we went to
>> each
>>> node and did a 'killall java' - in some cases I had to do 'killall -9
>> java'.
>>> My question : why is is this happening and what would be recommendations
>> , how
>>> to make sure that there is no hadoop processes running after I stopped
>> hadoop
>>> with stop-all.sh?
>>> 2) Also we have a dead node. We  removed this node  from
>>> $HADOOP_HOME/conf/slaves.  This file is supposed to tell the namenode
>>>  which machines are supposed to be datanodes/tasktrackers.
>>> We  started hadoop again, and were surprised to see a dead node in
>>  hadoop
>>> 'report' ("$HADOOP_HOME/bin/hadoop dfsadmin -report|less")
>>> It is only after blocking a deadnode and restarting hadoop, deadnode no
>> longer
>>> showed up in hreport.
>>> Any recommendations, how to deal with dead nodes?

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