Apache HBase (TM) emits Hadoop metrics.
First read up on Hadoop metrics. If you are using ganglia, the GangliaMetrics wiki page is useful read.
To have HBase emit metrics, edit $HBASE_HOME/conf/hadoop-metrics.properties and enable metric 'contexts' per plugin. As of this writing, hadoop supports file and ganglia plugins. Yes, the hbase metrics files is named hadoop-metrics rather than hbase-metrics because currently at least the hadoop metrics system has the properties filename hardcoded. Per metrics context, comment out the NullContext and enable one or more plugins instead.
If you enable the hbase context, on regionservers you'll see total requests since last metric emission, count of regions and storefiles as well as a count of memstore size. On the master, you'll see a count of the cluster's requests.
Enabling the rpc context is good if you are interested in seeing metrics on each hbase rpc method invocation (counts and time taken).
The jvm context is useful for long-term stats on running hbase jvms -- memory used, thread counts, etc. As of this writing, if more than one jvm is running emitting metrics, at least in ganglia, the stats are aggregated rather than reported per instance.
In addition to the standard output contexts supported by the Hadoop metrics package, you can also export HBase metrics via Java Management Extensions (JMX). This will allow viewing HBase stats in JConsole or any other JMX client.
To enable JMX support in HBase, first edit $HBASE_HOME/conf/hadoop-metrics.properties to support metrics refreshing. (If you've running 0.94.1 and above, or have already configured hadoop-metrics.properties for another output context, you can skip this step).
# Configuration of the "hbase" context for null
hbase.class=org.apache.hadoop.metrics.spi.NullContextWithUpdateThread
hbase.period=60
# Configuration of the "jvm" context for null
jvm.class=org.apache.hadoop.metrics.spi.NullContextWithUpdateThread
jvm.period=60
# Configuration of the "rpc" context for null
rpc.class=org.apache.hadoop.metrics.spi.NullContextWithUpdateThread
rpc.period=60
For remote access, you will need to configure JMX remote passwords and access profiles. Create the files:
monitorRole monitorpass
controlRole controlpass
monitorRole readonly
controlRole readwrite
Finally, edit the $HBASE_HOME/conf/hbase-env.sh script to add JMX support:
Add the lines:
HBASE_JMX_OPTS="-Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.ssl=false"
HBASE_JMX_OPTS="$HBASE_JMX_OPTS -Dcom.sun.management.jmxremote.password.file=$HBASE_HOME/conf/jmxremote.passwd"
HBASE_JMX_OPTS="$HBASE_JMX_OPTS -Dcom.sun.management.jmxremote.access.file=$HBASE_HOME/conf/jmxremote.access"
export HBASE_MASTER_OPTS="$HBASE_JMX_OPTS -Dcom.sun.management.jmxremote.port=10101"
export HBASE_REGIONSERVER_OPTS="$HBASE_JMX_OPTS -Dcom.sun.management.jmxremote.port=10102"
After restarting the processes you want to monitor, you should now be able to run JConsole (included with the JDK since JDK 5.0) to view the statistics via JMX. HBase MBeans are exported under the hadoop domain in JMX.
For more information on understanding HBase metrics, see the metrics section in the Apache HBase Reference Guide.