Driven FAQ
version 2.2.6Driven FAQ
Can I run my own Driven Server locally on-premise or remotely at my cloud or hosting provider?
Yes, you can deploy Driven in both environments with a trial license, which you can obtain on the Driven Trial registration page.
What versions of Hadoop are supported?
Driven works with any version of Hadoop that is compatible with Cascading. See the Cascading compatibility matrixes for the full list of supported versions.
What versions of the JDK are supported?
The matrix of supported JDKs is on the Cascading compatibility matrices page.
Does the Driven Plugin affect the execution of the application?
If your application executes successfully without the Driven Plugin, it executes successfully whether or not the Driven Plugin transmits all the telemetry data successfully. The push of the data to the Driven Server is decoupled from the execution of the MapReduce application.
How can I ensure that I see the application execution data that the Driven Plugin detects?
The multilayered Driven web client renders much of the application performance data that the plugin sends. Provided that the Driven Server and the plugin are operational and connected, you should not typically need to go beyond the Driven graphical user interface to discover the information that you need.
An "archive mode" configuration is available for the plugin, which writes to disk all data that is sent by the plugin. The archive can be "replayed" to view the information in a log-like format. Archive mode allows you to view data transmitted from the plugin when the Driven Server is not functioning or cannot be accessed. The archive also provides additional details of application execution that are not displayed in the Driven web client.
To use archive mode:
Either pass the following JVM property to the job:
-Dcascading.management.document.service.archive.dir=/path/to/archive
Or you can set the HADOOP_OPTS environment variable:
$ export HADOOP_OPTS="$HADOOP_OPTS -Dcascading.management.document.service.archive.dir=/path/to/archive"The compressed archive files are saved to path names that consist of the application name and the ID. Do not use ~ expansion for the path.
I am seeing errors on startup about not being able to write to some directories
By default the Driven webapp uses standard directories that should be accessible
to any webapp. If your particular installation does not allow this Driven can be
configured to store data somewhere other than the /var/lib/tomcat7/driven
default and to write logs somewhere other than the /usr/share/tomcat7/logs
default.
I am seeing out-of-memory errors. What are the possible causes?
OOM messages from the Driven Plugin are most likely a symptom of an error rather than an error itself.
Some possible underlying reasons for the OOM messages are:
-
The Cascading application is transmitting data to the Driven Plugin at a rate faster than the plugin can send the data to the Driven Server.
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The Driven Server is unavailable.
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The Cascading application is unable to connect to the Driven Server.
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A cluster is inadequately provisioned for NameNode processes and the machine (Driven Plugin pings the NameNode for slice information). Try changing the
-Xmsand-Xmxsettings of your application and NameNode processes to the following:-Xms4096m-Xmx4096m
If your application executes successfully without the Driven Plugin, it will execute successfully whether or not the Driven Plugin transmits all the telemetry data successfully. The push of the data to the Driven Server is decoupled from the execution of the MapReduce application.
I am seeing "java.io.IOException: java.util.prefs.BackingStoreException: Couldn’t get file lock" when installing a license
This is an issue with Java’s Preferences handling and some OS setups. The user
your webapp runs under (typically tomcat or tomcat7) needs write permissions
on its home directory.