Log4j settings Ambari uses sets of properties called Log4j properties to
control logging activities for each service running in your Hadoop cluster.
Initial, default values for each property reside in a <service_name>-log4j
template file. To access the default Log4j settings for a service; in
Ambari Web, you can browse to <Service_name> >
Configs > Advanced <service_name>-log4j. Often, user might want to configure the number of backup log
files or limit the maximum size of a log file. Prior to Ambari-2.5, this had to
be done by manually searching for the property in the log4j template Text Area
and modifying it. This is quite inconvenient. Ambari-2.4 and before Ambari-2.5 With Ambari-2.5, a simplified log rotation configuration
is provided i.e Log4j properties and values that limit the size and number of
backup log files for each service now appear above the log4j template file as
separate fields. Steps 1.Edit the values for the <service_name> backup
file size and <service_name> #
of backup files properties. 2.Click Save. Typically, once you modify these properties a restart
indicator shows up next to the relevant components. Restarting components in
the service pushes the configuration properties to each host running components
for that service. Fresh Install Ambari-2.5 These settings are readily available for any fresh install
of Ambari-2.5 Ambari 2.x
(x<5) Stack Upgrade These settings will be added during any stack upgrade. Ambari-2.x to Ambari-2.5 After upgrading Ambari from version 2.x to 2.5.0, if you
want to utilize the simplified log rotation configuration, you must update
configurations for all services in your cluster, using the following steps HDFS In Ambari Web, browse to HDFS > Configs > Advanced. Scroll down to Custom
HDFS-log4j. In Custom
HDFS-log4j, click Add Property. In Add Property,
type the following properties and values: hadoop_security_log_max_backup_size
= 256 hadoop_security_log_number_of_backup_files
= 20 hadoop_log_max_backup_size
= 256 hadoop_log_number_of_backup_files
= 10 Click Add. Browse to Advanced
hdfs-log4j . In Advanced
hdfs-log4j content section, find and replace the following
properties and values: Find: hadoop.security.log.maxfilesize=
<value>MB Replace: hadoop.security.log.maxfilesize={{hadoop_security_log_max_backup_size}}MB Find: hadoop.security.log.maxbackupindex=20 Replace: hadoop.security.log.maxbackupindex={{hadoop_security_log_number_of_backup_files}} Find: log4j.appender.RFA.MaxFileSize=<value>MB Replace: log4j.appender.RFA.MaxFileSize={{hadoop_log_max_backup_size}}MB Find: log4j.appender.RFA.MaxBackupIndex=<value> Replace: log4j.appender.RFA.MaxBackupIndex={{hadoop_log_number_of_backup_files}} In Configs,
click Save.Restart HDFS,
as prompted. For more information refer : https://docs.hortonworks.com/HDPDocuments/Ambari-2.5.1.0/bk_ambari-upgrade/content/upgrading_log_rotation_configuration.html
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