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Hadoop >> mail # user >> Speed up node under replicated block during decomission

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Re: Speed up node under replicated block during decomission
You can configure the undocumented variable dfs.max-repl-streams to
increase the number of replications a data-node is allowed to handle
at one time. The default value is 2. [1]


[1] https://issues.apache.org/jira/browse/HADOOP-2606?focusedCommentId=12578700&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-12578700

On Fri, Aug 12, 2011 at 12:09 PM, Charles Wimmer <[EMAIL PROTECTED]> wrote:
> The balancer bandwidth setting does not affect decommissioning nodes.  Decommisssioning nodes replicate as fast as the cluster is capable.
> The replication pace has many variables.
>  Number nodes that are participating in the replication.
>  The amount of network bandwidth each has.
>  The amount of other HDFS activity at the time.
>  Total blocks being replicated.
>  Total data being replicated.
>  Many others.
> On 8/12/11 8:58 AM, "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> wrote:
> Hi All,
> I'm trying to decommission data node from my cluster.  I put the data node in the /usr/lib/hadoop/conf/dfs.hosts.exclude list and restarted the name nodes.  The under-replicated blocks are starting to replicate, but it's going down in a very slow pace.  For 1 TB of data it takes over 1 day to complete.   We change the settings as below and try to increase the replication rate.
> Added this to hdfs-site.xml on all the nodes on the cluster and restarted the data nodes and name node processes.
> <property>
>  <!-- 100Mbit/s -->
>  <name>dfs.balance.bandwidthPerSec</name>
>  <value>131072000</value>
> </property>
> Speed didn't seem to pick up. Do you know what may be happening?
> Thanks!
> Jonathan
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Joseph Echeverria
Cloudera, Inc.