Configuring Alluxio with HDFS

This guide describes how to configure Alluxio with HDFS as the under storage system.

Initial Setup

To run an Alluxio cluster on a set of machines, you must deploy Alluxio binaries to each of these machines. You can either compile the binaries from Alluxio source code, or download the precompiled binaries directly.

Note that, by default, Alluxio binaries are built to work with Hadoop HDFS version 2.2.0. To use another Hadoop version, one needs to recompile Alluxio binaries from source code with the correct Hadoop version set by either of following approaches. Assume ${ALLUXIO_HOME} is the root directory of Alluxio source code.

• Modify the hadoop.version tag defined in ${ALLUXIO_HOME}/pom.xml. E.g., to work with Hadoop 2.6.0, modify this pom file to set “<hadoop.version>2.6.0</hadoop.version>” instead of “<hadoop.version>2.2.0</hadoop.version>”. Then recompile the source using maven. To make compiling faster, you can add -DskipTests option to skip unit tests.

mvn clean package -DskipTests

• Alternatively, you can also pass the correct Hadoop version in command line when compiling with maven. For example, if you want Alluxio to work with Hadoop HDFS 2.6.0:

mvn -Dhadoop.version=2.6.0 clean package -DskipTests

If everything succeeds, you should see alluxio-assemblies-1.4.0-jar-with-dependencies.jar created in the assembly/target directory and this is the jar file you can use to run both Alluxio Master and Worker.

Configuring Alluxio

To run Alluxio binary, we must setup configuration files. Create your configuration file with bootstrapConf command. For example, if you are running Alluxio on your local machine, ALLUXIO_MASTER_HOSTNAME should be set to localhost

./bin/alluxio bootstrapConf <ALLUXIO_MASTER_HOSTNAME>

Alternatively, you can also create the configuration file from the template and set the contents manually.

cp conf/alluxio-env.sh.template conf/alluxio-env.sh

Then edit conf/alluxio-site.properties file to set the under storage address to the HDFS namenode address and the HDFS directory you want to mount to Alluxio. For example, the under storage address can be hdfs://localhost:9000 if you are running the HDFS namenode locally with default port and mapping HDFS root directory to Alluxio, or hdfs://localhost:9000/alluxio/data if only the HDFS directory /alluxio/data is mapped to Alluxio.

alluxio.underfs.address=hdfs://NAMENODE:PORT

Configuring Alluxio with HDFS namenode HA mode

If HDFS namenodes are running in HA mode, both Alluxio servers and clients should be configured properly in order to access HDFS.

For Alluxio servers (masters and workers), copy hdfs-site.xml and core-site.xml from your hadoop installation into ${ALLUXIO_HOME}/conf. Alternatively, you can set alluxio.underfs.hdfs.configuration to the hadoop property file hdfs-site.xml (or core-site.xml) in conf/alluxio-site.properties (make sure all the relative configurations are available in the file).

Then, set the under storage address to hdfs://nameservice/ (nameservice is the name of HDFS service already configured in core-site.xml) if you are mapping HDFS root directory to Alluxio, or hdfs://nameservice/alluxio/data if only the HDFS directory /alluxio/data is mapped to Alluxio.

alluxio.underfs.address=hdfs://nameservice/

Next, for Alluxio clients, alluxio.underfs.hdfs.configuration should also be set to the hadoop property file hdfs-site.xml (or core-site.xml).

Running Alluxio Locally with HDFS

Before this step, please make sure your HDFS cluster is running and the directory mapped to Alluxio exists. After everything is configured, you can start up Alluxio locally to see that everything works.

./bin/alluxio format
./bin/alluxio-start.sh local

This should start one Alluxio master and one Alluxio worker locally. You can see the master UI at http://localhost:19999.

Next, you can run a simple example program:

./bin/alluxio runTests

After this succeeds, you can visit HDFS web UI at http://localhost:50070 to verify the files and directories created by Alluxio exist. For this test, you should see files named like: /default_tests_files/BasicFile_STORE_SYNC_PERSIST

You can stop Alluxio any time by running:

./bin/alluxio-stop.sh all