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https://issues.apache.org/jira/browse/AMBARI-12252?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Alejandro Fernandez updated AMBARI-12252:
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Attachment: AMBARI-12252.patch
AMBARI-12252.branch-2.1.patch
> Prevent datanode from creating an HDFS datadir when drive becomes unmounted
> ---------------------------------------------------------------------------
>
> Key: AMBARI-12252
> URL: https://issues.apache.org/jira/browse/AMBARI-12252
> Project: Ambari
> Issue Type: Bug
> Components: ambari-agent
> Affects Versions: 1.7.0
> Reporter: Alejandro Fernandez
> Assignee: Alejandro Fernandez
> Priority: Critical
> Fix For: 2.1.0
>
> Attachments: AMBARI-12252.branch-2.1.patch, AMBARI-12252.patch
>
>
> This is related to AMBARI-7506
> Ambari keeps track of a file, /etc/hadoop/conf/dfs_data_dir_mount.hist
> that contains a mapping of HDFS data dirs to the last known mount point.
> This is used to detect when a data dir becomes unmounted, in order to prevent
> HDFS from writing to the root partition.
> Consider the example of a data node configured with these volumes:
> /dev/sda -> /
> /dev/sdb -> /grid/0
> /dev/sdc -> /grid/1
> /dev/sdd -> /grid/2
> Typically, each /grid/#/ directory contains a data folder.
> Today, if a data directory becomes unmounted, then the directory will not
> exist and Ambari will not create it automatically. Ambari will simply log a
> warning, and update its cache with the new mount point, which is / ; that is
> the underlying bug.
> If hdfs-site contains dfs.datanode.failed.volumes.tolerated with a value > 0,
> then DataNode will tolerate the failure, otherwise, the DataNode will die.
> Because Ambari will already have "/" in its cache file, the fact that it used
> to be mounted in a non-root drive is lost, so next time DataNode is
> restarted, Ambari will create the data dir which is now mounted on the root
> partition; this is really bad because HDFS will now fill up the root drive.
> The admin can still remount the partition, but then needs to restart DataNode
> so Ambari can update its cache.
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