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List:       hadoop-user
Subject:    RE: How to add new journal nodes without service downtime?
From:       "Fu, Yong" <yong.fu () intel ! com>
Date:       2017-10-31 12:03:24
Message-ID: E55525BD360D9249AC15FA039225DF5F31EE183F () SHSMSX101 ! ccr ! corp ! intel ! com
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From Cloudera's guide, there should have a downtime when moving Jounal Nodes:
https://www.cloudera.com/documentation/enterprise/5-7-x/topics/admin_nn_migrate_roles.html#concept_w3h_m2l_2r


And a ticket from Community about this problem which is still unresolved:
https://issues.apache.org/jira/browse/HDFS-10665

For the exceptional journal node, do you have tried to collect system metrics and \
profile it possibly to identify the root cause?

From: 孙锐 [mailto:rui.sun@tongdun.cn]
Sent: Thursday, October 26, 2017 11:06 AM
To: user@hadoop.apache.org
Subject: How to add new journal nodes without service downtime?

HI, folks,

We are using Hadoop 2.6.0 (CDH version) with 3 journal nodes.  We want to add 2 more \
journal nodes to the existing 3 ones. We tried to add nodes without service downtime \
according to some posts in the community, but that seems not reliable. It seems that \
adding or moving journal nodes requires downtime of the HDFS service. Is this \
correct?

Another question is that if one Journal node has been down or slow for some time (lag \
far way behind other journal nodes),  can the journal node be brought back to work by \
simply restarting it? Or  moving it to another machine is required?

It seems that operational guide for journal nodes is missing in the official \
documentation.

Thanks,
Ray


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<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">From Cloudera's \
guide, there should have a downtime when moving Jounal Nodes:<o:p></o:p></span></p> \
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><a \
href="https://www.cloudera.com/documentation/enterprise/5-7-x/topics/admin_nn_migrate_ \
roles.html#concept_w3h_m2l_2r">https://www.cloudera.com/documentation/enterprise/5-7-x/topics/admin_nn_migrate_roles.html#concept_w3h_m2l_2r</a><o:p></o:p></span></p>
 <p class="MsoNormal"><span \
style="font-size:11.0pt;color:#1F497D"><o:p>&nbsp;</o:p></span></p> <p \
class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">And a ticket from \
Community about this problem which is still unresolved:<o:p></o:p></span></p> <p \
class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><a \
href="https://issues.apache.org/jira/browse/HDFS-10665">https://issues.apache.org/jira/browse/HDFS-10665</a><o:p></o:p></span></p>
 <p class="MsoNormal"><span \
style="font-size:11.0pt;color:#1F497D"><o:p>&nbsp;</o:p></span></p> <p \
class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">For the exceptional \
journal node, do you have tried to collect system metrics and profile it possibly to \
identify the root cause?<o:p></o:p></span></p> <p class="MsoNormal"><a \
name="_MailEndCompose"><span \
style="font-size:11.0pt;color:#1F497D"><o:p>&nbsp;</o:p></span></a></p> <div>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><a name="_____replyseparator"></a><b><span \
style="font-size:11.0pt">From:</span></b><span style="font-size:11.0pt"> </span><span \
lang="ZH-CN" style="font-size:11.0pt;font-family:&quot;Microsoft \
YaHei&quot;,sans-serif">孙锐</span><span style="font-size:11.0pt"> \
[mailto:rui.sun@tongdun.cn] <br>
<b>Sent:</b> Thursday, October 26, 2017 11:06 AM<br>
<b>To:</b> user@hadoop.apache.org<br>
<b>Subject:</b> How to add new journal nodes without service \
downtime?<o:p></o:p></span></p> </div>
</div>
<p class="MsoNormal"><o:p>&nbsp;</o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt">HI, folks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p>&nbsp;</o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">We are using Hadoop 2.6.0 (CDH \
version) with 3 journal nodes.&nbsp; We want to add 2 more journal nodes to the \
existing 3 ones. We tried to add nodes without service downtime according to some \
posts in the community,  but that seems not reliable. It seems that adding or moving \
journal nodes requires downtime of the HDFS service. Is this \
correct?<o:p></o:p></span></p> <p class="MsoNormal"><span \
style="font-size:11.0pt"><o:p>&nbsp;</o:p></span></p> <p class="MsoNormal"><span \
style="font-size:11.0pt">Another question is that if one Journal node has been down \
or slow for some time (lag far way behind other journal nodes), &nbsp;can the journal \
node be brought back to work by simply restarting it? Or &nbsp;moving  it to another \
machine is required? <o:p></o:p></span></p> <p class="MsoNormal"><span \
style="font-size:11.0pt"><o:p>&nbsp;</o:p></span></p> <p class="MsoNormal"><span \
style="font-size:11.0pt">It seems that operational guide for journal nodes is missing \
in the official documentation.<o:p></o:p></span></p> <p class="MsoNormal"><span \
style="font-size:11.0pt"><o:p>&nbsp;</o:p></span></p> <p class="MsoNormal"><span \
style="font-size:11.0pt">Thanks,<o:p></o:p></span></p> <p class="MsoNormal"><span \
style="font-size:11.0pt">Ray<o:p></o:p></span></p> <p class="MsoNormal"><span \
style="font-size:11.0pt"><o:p>&nbsp;</o:p></span></p> <p class="MsoNormal"><span \
style="font-size:11.0pt"><o:p>&nbsp;</o:p></span></p> </div>
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