Creating the gpperfmon Database

Enabling the Collection Agents
Configuring a Standby Master Host (if enabled)
gpmon User Authentication

This topic describes how to create the Command Center gpperfmon database and enable the data collection agents. This task must be completed one time for the Greenplum Database system, before you create a Greenplum Command Center instance.

When the data collection agents are enabled, their processes are started and stopped (using gpstart and gpstop) on the Greenplum segment hosts along with the Greenplum Database server processes.

Greenplum provides a gpperfmon_install utility that performs the following tasks:

Creates the Command Center database (gpperfmon).
Creates the Command Center superuser role (gpmon).
Configures Greenplum Database server to accept connections from the gpmon role (edits the pg_hba.conf and .pgpass files).
Sets the Command Center server configuration parameters in the Greenplum Database server postgresql.conf files.

The gpperfmon_install utility and the agents are part of the Greenplum Database software. The tasks in this topic can be performed before or after the Command Center software is installed.

Enabling the Collection Agents

Log in to the Greenplum master host as the gpadmin user.
```
$ su - gpadmin
```
Source the path file from the Greenplum Database installation directory:
```
# source /usr/local/greenplum-db/greenplum_path.sh
```
Run the gpperfmon_install utility with the --enable option. You must supply the connection port of the Greenplum Database master server process, and set the password for the gpmon superuser that will be created. For example:
```
$ gpperfmon_install --enable --password changeme --port 5432
```
Note:
The gpperfmon_install utility creates entries for the gpmon user in the $MASTER_DATABASE/pg_hba.conf file. See gpmon User Authentication for notes about restricting the gpmon user’s access to databases.

The password you specify is saved in a .pgpass file in the gpadmin user’s home directory. See Changing the gpmon Password for steps to change the gpmon password.
When the utility completes, restart Greenplum Database server. The data collection agents do not start until the database is restarted.
```
$ gpstop -r
```
Using the ps command, verify that the data collection process is running on the Greenplum master. For example:
```
$ ps -ef | grep gpmmon
```
Run the following command to verify that the gpmon user can authenticate and that the data collection processes are writing to the Command Center database. If all of the segment data collection agents are running, you should see one row per segment host.
```
$ psql -U gpmon gpperfmon -c 'SELECT * FROM system_now;'
```

The data collection agents are now running, and your Greenplum system now has a gpperfmon database installed. This is the database where Command Center data is stored. You can connect to it as follows:

$ psql gpperfmon

Configuring a Standby Master Host (if enabled)

Copy the $MASTER_DATA_DIRECTORY/pg_hba.conf file from your primary master host to your standby master host. This ensures that the required connection options are also set on the standby master.
Copy your ~/.pgpass file from your primary master host to your standby master host. This file usually resides in the gpadmin user’s home directory. Note that the permissions on .pgpass must be set to 600 (for example: chmod 0600 ~/.pgpass).

gpmon User Authentication

The gperfmon_install utility adds the gpmon user to the pg_hba.conf authorization configuration file entries allowing local connections to any database in the Greenplum cluster. Greenplum Command Center requires that the gpmon user have access to gpperfmon and every database that Command Center will monitor. Since the gpmon role is a Greenplum Database superuser, you may wish to restrict the role from accessing other databases. Edit the $MASTER_DATA_DIRECTORY/pg_hba.conf and edit these lines:

local    gpperfmon   gpmon         md5
host     all         gpmon         127.0.0.1/28    md5
host     all         gpmon         ::1/128         md5

List gpperfmon and the databases you want to monitor with Command Center in the second field:

local    gpperfmon,userdb1,userdb2   gpmon                         md5
host     gpperfmon,userdb1,userdb2   gpmon         127.0.0.1/28    md5
host     gpperfmon,userdb1,userdb2   gpmon         ::1/128         md5

See Changing the gpmon Password for steps to change the gpmon user’s password.