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https://issues.apache.org/jira/browse/HDFS-6688?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14062875#comment-14062875
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Andrew Wang commented on HDFS-6688:
-----------------------------------
I admit we don't have the greatest (any?) documentation for metrics. Typically
I have to dig around in the code. The stale node feature I don't think has much
in the way of docs either, so if you see a good place to add a mention, we'd
happily take a docs patch.
The 10.5 mins is also somewhat configurable. It's calculated from this in
DatanodeManager:
{code}
this.heartbeatExpireInterval = 2 * heartbeatRecheckInterval
+ 10 * 1000 * heartbeatIntervalSeconds;
{code}
So if you adjust "dfs.namenode.heartbeat.recheck-interval" and
"dfs.heartbeat.interval" you have some control.
> Hadoop JMX stats are not refreshed
> ----------------------------------
>
> Key: HDFS-6688
> URL: https://issues.apache.org/jira/browse/HDFS-6688
> Project: Hadoop HDFS
> Issue Type: Bug
> Environment: Ubuntu
> Reporter: Biju Nair
>
> Even when the HDFS datanode process is stopped the JMX attribute
> Hadoop.NameNode.FSNamesystemState.NumLiveDataNodes/NumDeadDataNodes attribute
> values doesn't change. Also Hadoop.NameNode.NameNodeInfo.Attributes.LiveNodes
> shows the stopped datanode details. If these attributes reflect the actual
> changes in the datanode, they can be used to monitor the health of the HDFS
> cluster which currently can't be used.
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