Chapter 9. HDP Logfiles - Hortonworks Data Platform

1. HDP Log Locations

Each component of the HDP ecosystem creates logs from each of the daemons under normal operation, as well as configuration logs, statistics, standard error, standard out, and internal diagnostic information.

The following table for HDP 1.3 lists the types of logs and where you can find them. The locations depend on the user that owns the process. For example, $hdfs represents the system user that owns the HDFS component daemons.

Table 9.1. Dependencies on HDP components

Component	Log Type	Log Location (defaults)
HDFS	NameNode operational logs	On NameNode - `/var/log/hadoop/$hdfs`
HDFS	DataNode operational logs	On DataNodes - `/var/log/hadoop/$hdfs`
MapReduce (HDP 1.x)	Job Tracker operational logs	On JobTracker - `/var/log/hadoop/$mapred`
MapReduce (HDP 1.x)	Task Tracker operational logs	On TaskTrackers - `/var/log/hadoop/$mapred`
MapReduce (HDP 1.x)	MapReduce Job logs	On TaskTrackers - `/var/log/hadoop/$mapred/userlogs`
Hive	HiveServer2 operational logs	On HiveServer2 - `/var/log/hive/hive-server2.*`
Hive	Hive Metastore operational logs	On Hive Metastore - `/var/log/hive/hive.*`
WebHCat	WebHCat Server operational logs	On WebHCat server - `/var/log/webhcat`
Oozie	Oozie Server operational logs	On Oozie Server - `/var/log/oozie`
HBase	HBase Master operational logs	On HBase Master - `/var/log/hbase`
HBase	Region Server operational logs	On RegionServers - `/var/log/hbase`
ZooKeeper	ZooKeeper operational logs	On ZooKeeper nodes - `/var/log/zookeeper`
Nagios	Nagios Server operational logs	On the Nagios Server - `/var/log/nagios` Log Archive Path - `/var/log/nagios/archives`
Ganglia	Ganglia Server	On the Ganglia Server - `/var/log/messages`
Ganglia	Ganglia Monitor	On Ganglia Monitor nodes - `/var/log/messages`
Ambari	Ambari Server	On Ambari Server - `/var/log/ambari-server`
Ambari	Ambari Agent	On Ambari Server - `/var/log/ambari-server`

2. HDP Log Format

Hadoop and the other HDP components use Log4J to format their log files, and to filter what information is logged. The log format and filter can be configured for each component by editing the corresponding log4j.properties file. These files are found in the configuration folders for each component. The following log4j severity levels are available to filter logs:

OFF- Highest possible rank. Turns off all logging.
FATAL - Application will probably abort due to these errors. Displays on the status console.
ERROR - Runtime errors or unexpected conditions. Application may continue to run. Displays on console.
WARN - Undesirable or unexpected conditions. Potentially danerous conditions. Displays on console.
INFO - Interesting messages on application progress. Displays on console.
DEBUG - Detailed information on events to debug an application. Written to logs only.
TRACE - More detailed information than DEBUG to help debug an application. Written to logs only.
ALL - Lowest possible rank. Turns on all logging.

	Note
	If you do not assign a logging level to the logger, the logger inherits the first non-null level in the hirearchy. By default, the root logger is at the DEBUG logging level.

3. HDP Backups

You can back up your HDP clusters to an external backup HDP cluster using distcp, a bulk data movement tool. Invoke distcp periodically to transfer HDFS datasets from the active HDP cluster to the backup HDP cluster.

For more information on backing up clusters with distcp, visit the distcp community page here.