Database Reference
In-Depth Information
UI
HBase runs a web server on the master to present a view on the state of your running
cluster. By default, it listens on port 60010. The master UI displays a list of basic attrib-
utes such as software versions, cluster load, request rates, lists of cluster tables, and parti-
cipating regionservers. Click on a regionserver in the master UI, and you are taken to the
web server running on the individual regionserver. It lists the regions this server is carry-
ing and basic metrics such as resources consumed and request rates.
Metrics
Hadoop has a metrics system that can be used to emit vitals over a period to a
context
(this
is covered in
Metrics and JMX
)
. Enabling Hadoop metrics, and in particular tying them to
Ganglia or emitting them via JMX, will give you views on what is happening on your
cluster, both currently and in the recent past. HBase also adds metrics of its own — re-
quest rates, counts of vitals, resources used. See the file
hadoop-metric-
s2-hbase.properties
under the HBase
conf
directory.
Counters
At
StumbleUpon
,
the first production feature deployed on HBase was keeping counters
for the stumbleupon.com frontend. Counters were previously kept in MySQL, but the rate
of change was such that drops were frequent, and the load imposed by the counter writes
was such that web designers self imposed limits on what was counted. Using the
incre-
mentColumnValue()
method on
HTable
, counters can be incremented many thou-
sands of times a second.
