Administering Command Center Agents

The Command Center metrics collection agent, ccagent, runs on segment hosts and receives real-time metrics emitted by the metrics collection database extension. Each segment host has one ccagent process. The metrics collection extension connects to ccagent using Unix Domain Sockets (UDS) to transfer metrics from Greenplum Database. Starting Greenplum Command Center with the gpcc start command starts the Command Center agent on each segment host. Stopping Command Center with gpcc stop ends these processes. The Command Center backend monitors these agents and restarts them when necessary.

This topic describes basic agent administration tasks, including enabling agents after adding hosts to the cluster and viewing the agent log files.

About the gpperfmon Data Collection Agents

The Greenplum Database gpperfmon_install utility enables the gpmmon and gpsmon data collection agents. Greenplum Command Center no longer requires the history data these agents collect. You can run the gpperfmon data collection agents and the Command Center metrics collection agents in parallel, but unless you need the data the gpperfmon agents collect for some other purpose, you can improve the Greenplum Database system performance by disabling the gpperfmon agents.

To see if the gpperfmon agents are enabled, check the gp_enable_gpperfmon server parameter with the following command.

$ gpconfig -s gp_enable_gpperfmon

If the gp_enable_gpperfmon parameter is on, disable the agents by setting the parameter to off and restarting Greenplum Database.

$ gpconfig -c gp_enable_perform -v off
$ gpstop -ar

For more information about the gpperfmon data collection agents see gpperfmon_install in the Greenplum Database Utility Reference.

Configuring gpmon Role Logging Options

The metrics collection agent ccagent runs queries on Greenplum Database on behalf of Command Center to perform activities such as retrieving information to display in the Command Center UI, saving state in the gpperfmon and postgres databases, inserting alert event records, and harvesting query history for the gpmetrics history tables. The agent runs these queries using the gpmon database role.

If you do not want all of this query activity to be logged in the pg_log log file, you can set logging options for the gpmon role using the ALTER ROLE command. For example, these commands set the gpmon role to log only DDL statements (CREATE, ALTER, DROP) and to log only fatal and panic errors.

ALTER ROLE gpmon SET log_statement TO DDL;
ALTER ROLE gpmon SET log_min_messages to FATAL;

See the log_statement and log_min_messages server configuration parameters in the Greenplum Database documentation for logging options.

Adding and Removing Hosts

When you add or replace Greenplum Database hosts, you must reinstall the Greenplum Command Center software to ensure the software is installed on the new hosts. It is not necessary to uninstall Command Center before reinstalling.

Viewing and Maintaining Agent Log Files

Log messages for the Command Center metrics collector agents are saved in the logs directory of the Command Center installation directory on the master and each segment host.

The current log file is named agent.log. When a new log is started, the current log is renamed to agent.<timestamp>.log and a new agent.log file is opened. You should remove old log files regularly to recover space.