Alejandro Fernandez created AMBARI-12267:
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Summary: Ambari to improve tracking of data dirs becoming
unmounted.
Key: AMBARI-12267
URL: https://issues.apache.org/jira/browse/AMBARI-12267
Project: Ambari
Issue Type: Story
Components: ambari-agent
Affects Versions: 2.0.0
Reporter: Alejandro Fernandez
Assignee: Alejandro Fernandez
Fix For: 2.2.0
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.
If hdfs-site contains dfs.datanode.failed.volumes.tolerated with a value > 0,
then DataNode will tolerate the failure, otherwise, the DataNode will die.
In AMBARI-12252, I fixed a bug so that Ambari would prevent an unmounted drive
from allowing HDFS to write to the root partition.
However, this approach relies on the /etc/hadoop/conf/dfs_data_dir_mount.hist
file existing, and the original configuration being correct.
The ideal way to fix this is,
* Track which data dirs the admin wants mounted on a non-root partition. If the
admin wishes all data dirs to be on non-root mounts, but the initial install is
incorrect, then this should be reported as a problem.
* Keep the history of the mount points in the database. Today, if the cache
file is deleted or the host reimaged, then this information is lost.
* Introduce a new state between FAILED and COMPLETED, such as
COMPLETED_WITH_ERRORS, that will allow tasks to look differently in the UI, so
the user can clearly detect when a critical but non fatal error happened.
Plugin with Alert Framework
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