The following sections outline the various ways in which JanusGraph can be used in concert with Apache HBase.

$ ./bin/start-hbase.sh
starting master, logging to ../logs/hbase-master-machine-name.local.out

JanusGraph graph = JanusGraphFactory.build()
	.set("storage.backend", "hbase")
	.open();

JanusGraph g = JanusGraphFactory.build()
	.set("storage.backend", "hbase")
	.set("storage.hostname", "77.77.77.77, 77.77.77.78, 77.77.77.79")
	.open();

http://gremlin-server.janusgraph.machine1/mygraph/vertices/1
http://gremlin-server.janusgraph.machine2/mygraph/tp/gremlin?script=g.v(1).out('follows').out('created')

...
graphs: {
  g: conf/janusgraph-hbase.properties}
plugins:
  - janusgraph.imports
...

Refer to Chapter 13, Configuration Reference for a complete listing of all HBase specific configuration options in addition to the general JanusGraph configuration options.

When configuring HBase it is recommended to consider the following HBase specific configuration options:

Please refer to the HBase configuration documentation for more HBase configuration options and their description. By prefixing the respective HBase configuration option with storage.hbase.ext in the JanusGraph configuration it will be passed on to HBase at initialization time. For example, to use the znode /hbase-secure for HBase, set the property: storage.hbase.ext.zookeeper.znode.parent=/hbase-secure. The prefix allows arbitrary HBase configuration options to be configured through JanusGraph.

	Important
	HBase backend uses millisecond for timestamps. In JanusGraph 0.2.0 and earlier, if the graph.timestamps property is not explicitly set, the default is MICRO. In this case, the graph.timestamps property must be explicitly set to MILLI. Do not set the graph.timestamps property to another value in any cases.

JanusGraph over HBase supports global vertex and edge iteration. However, note that all these vertices and/or edges will be loaded into memory which can cause OutOfMemoryException. Use Chapter 35, JanusGraph with TinkerPop’s Hadoop-Gremlin to iterate over all vertices or edges in large graphs effectively.

Follow these steps to setup an HBase cluster on EC2 and deploy JanusGraph over HBase. To follow these instructions, you need an Amazon AWS account with established authentication credentials and some basic knowledge of AWS and EC2.

The following commands first launch a four-node HBase cluster on EC2 via Whirr, then run a basic JanusGraph test case using the cluster.

The configuration described below puts one HBase master server in charge of three HBase regionservers. The master will be the sole member of the Zookeeper quorum by which JanusGraph connects to HBase.

Whirr 0.7.1 sometimes fails when run on a machine behind a NAT WHIRR-459. For this reason, it’s recommended to use at least Whirr 0.7.2. Whirr 0.8.0 was used to test the following commands on a t1.micro instance running Amazon Linux 2012.03. These commands might need tweaking to produce the intended results on environments besides a t1.micro instance running Amazon Linux 2012.03.

# These commands were executed on a t1.micro instance running Amazon Linux 2012.03 x86_64.
# The AMI identifier for Amazon Linux 2012.03 x86_64 is ami-aecd60c7.
# https://console.aws.amazon.com/ec2/home?region=us-east-1#launchAmi=ami-aecd60c7
export AWS_ACCESS_KEY_ID=... # Set your Access Key here
export AWS_SECRET_ACCESS_KEY=... # Set your Secret Key here
curl -O http://www.apache.org/dist/whirr/whirr-0.8.0/whirr-0.8.0.tar.gz
tar -xzf whirr-0.8.0.tar.gz && cd whirr-0.8.0
# Generate an SSH keypair with which Whirr will deploy and manage instances
ssh-keygen -t rsa -P '' -f ~/.ssh/id_rsa_whirr
# Download a Whirr recipe for deploying HBase 0.94.1 with hadoop-core 1.0.3
pushd recipes && wget 'https://raw.github.com/JanusGraph/janusgraph/master/config/whirr-hbase.properties' ; popd
bin/whirr launch-cluster --config recipes/whirr-hbase.properties --private-key-file ~/.ssh/id_rsa_whirr
# Run a superficial health check on the hbase-master node (this should print "imok")
echo "ruok" | nc $(awk '{print $3}' ~/.whirr/hbase-testing/instances | head -1) 2181; echo
# Login to the HBase master node to run the remaining commands
ssh -i ~/.ssh/id_rsa_whirr -o "UserKnownHostsFile /dev/null" \
      -o StrictHostKeyChecking=no \
      `grep hbase-master ~/.whirr/hbase-testing/instances \
      | awk '{print $3}'`
# Maven 2 is available through the package manager, but an incompatibility
# with surefire 2.12 makes it a pain to use; here we download Maven 3 without
# the OS package manager
wget 'http://archive.apache.org/dist/maven/maven-3/3.0.4/binaries/apache-maven-3.0.4-bin.tar.gz'
tar -xzf apache-maven-3.0.4-bin.tar.gz
# Install git
sudo apt-get install -y git-core
# Clone JanusGraph
git clone 'git://github.com/JanusGraph/janusgraph.git' && cd janusgraph
# Run a HBase-backed test of JanusGraph
#
# This test should produce pages of output ending in something like this:
#
# -------------------------------------------------------
#  T E S T S
# -------------------------------------------------------
# Running org.janusgraph.graphdb.hbase.ExternalHBaseGraphPerformanceTest
# Starting trial 1/1
# 10000
# 20000
# 30000
# 40000
# 50000
# Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 303.659 sec
#
# Results :
#
# Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
#
# [INFO] ------------------------------------------------------------------------
# [INFO] BUILD SUCCESS
# [INFO] ------------------------------------------------------------------------
~/apache-maven-3.0.4/bin/mvn test -Dtest=ExternalHBaseGraphPerformanceTest#unlabeledEdgeInsertion
# Check on hadoop
hadoop version # Should print 1.0.3
# List the hadoop root; should print something like:
#
# Found 4 items
# drwxr-xr-x   - hadoop supergroup          0 2012-09-20 00:20 /hadoop
# drwxr-xr-x   - hadoop supergroup          0 2012-09-20 00:42 /hbase
# drwxrwxrwx   - hadoop supergroup          0 2012-09-20 00:20 /tmp
# drwxrwxrwx   - hadoop supergroup          0 2012-09-20 00:20 /user
hadoop fs -ls /

The HBase shell on the master server can be used to get an overall status check of the cluster.

$HBASE_HOME/bin/hbase shell

From the shell, the following commands are generally useful for understanding the status of the cluster.

status 'janusgraph'
status 'simple'
status 'detailed'

The above commands can identify if a region server has gone down. If so, it is possible to ssh into the failed region server machines and do the following:

sudo -u hadoop $HBASE_HOME/bin/hbase-daemon.sh stop regionserver
sudo -u hadoop $HBASE_HOME/bin/hbase-daemon.sh start regionserver

The use of pssh can make this process easy as there is no need to log into each machine individually to run the commands. Put the IP addresses of the regionservers into a hosts.txt file and then execute the following.

pssh -h host.txt sudo -u hadoop $HBASE_HOME/bin/hbase-daemon.sh stop regionserver
pssh -h host.txt sudo -u hadoop $HBASE_HOME/bin/hbase-daemon.sh start regionserver

Next, sometimes you need to restart the master server (e.g. connection refused exceptions). To do so, on the master execute the following:

sudo -u hadoop $HBASE_HOME/bin/hbase-daemon.sh stop master
sudo -u hadoop $HBASE_HOME/bin/hbase-daemon.sh start master

Finally, if an HBase cluster has already been deployed and more memory is required of the master or region servers, simply edit the $HBASE_HOME/conf/hbase-env.sh files on the respective machines with requisite -Xmx -Xms parameters. Once edited, stop/start the master and/or region servers as described previous.