Adding and Removing Hosts
Segment agents on new hosts are detected automatically by the master agent. Whenever gp_enable_gpperfmon is enabled on the master, the master monitor agent automatically detects, starts, and begins harvesting data from new segment agents.
To verify the addition of a new monitored host, you can check for the new hostname in the Greenplum Command Center Console System Metrics view described in the Greenplum Command Center Console online help. Alternately, you can query the system_now table for the row containing current metrics for each host. For example:
=# SELECT * FROM system_now WHERE hostname='new_hostname';
Viewing and Maintaining Master Agent Log Files
Log messages for the master agent are written to $MASTER_DATA_DIRECTORY/gpperfmon/logs/gpmmon.log by default. To change the log file location, edit the log_location parameter in gpperfmon.conf.
On the segment hosts, agent log messages are written to a gpsmon.log file in the segment instance’s data directory. For a host with multiple segments, the agent log file is located in the data directory of the first segment, as listed in the gp_configuration table by dbid. If the segment agent is unable to log into this directory, it will log messages to the home directory of the user running Command Center (typically gpadmin).
Configuring Log File Rollover
At higher logging levels, the size of the log files may grow dramatically. To prevent the log files from growing to excessive size, you can add an optional log rollover parameter to gpperfmon.conf. The value of this parameter is measured in bytes. For example:
max_log_size = 10485760
With this setting, the log files will grow to 10MB before the system rolls over the log file. The timestamp is added to the log file name when it is rolled over. Administrators must periodically clean out old log files that are no longer needed.