Installing and Configuring Greenplum on all Hosts

When run as root, gpseginstall copies the Greenplum Database installation from the current host and installs it on a list of specified hosts, creates the Greenplum system user (gpadmin), sets the system user's password (default is changeme), sets the ownership of the Greenplum Database installation directory, and exchanges ssh keys between all specified host address names (both as root and as the specified system user).

About gpadmin

When a Greenplum Database system is first initialized, the system contains one predefined superuser role (also referred to as the system user), gpadmin. This is the user who owns and administers the Greenplum Database.

Note: If you are setting up a single node system, you can still use gpseginstall to perform the required system configuration tasks on the current host. In this case, the hostfile_exkeys would just have the current host name only.

To install and configure Greenplum Database on all specified hosts

Log in to the master host as root:
```
$ su -
```
Source the path file from your master host's Greenplum Database installation directory:
```
# source /usr/local/greenplum-db/greenplum_path.sh
```
Create a file called hostfile_exkeys that has the machine configured host names and host addresses (interface names) for each host in your Greenplum system (master, standby master and segments). Make sure there are no blank lines or extra spaces. For example, if you have a master, standby master and three segments with two network interfaces per host, your file would look something like this:
```
mdw
mdw-1
mdw-2
smdw
smdw-1
smdw-2
sdw1
sdw1-1
sdw1-2
sdw2
sdw2-1
sdw2-2
sdw3
sdw3-1
sdw3-2
```
Check the /etc/hosts file on your systems for the correct host names to use for your environment.

The Greenplum Database segment host naming convention is sdwN where sdw is a prefix and N is an integer. For example, on a Greenplum Database DCA system, segment host names would be sdw1, sdw2 and so on. For hosts with multiple interfaces, the convention is to append a dash (-) and number to the host name. For example, sdw1-1 and sdw1-2 are the two interface names for host sdw1.
Run the gpseginstall utility referencing the hostfile_exkeys file you just created. Use the -u and -p options to create the Greenplum system user (gpadmin) on all hosts and set the password for that user on all hosts. For example:
```
# gpseginstall -f hostfile_exkeys -u gpadmin -p P@$$word
```
Recommended security best practices:

Do not use the default password option for production environments.
Change the password immediately after installation.

Confirming Your Installation

To make sure the Greenplum software was installed and configured correctly, run the following confirmation steps from your Greenplum master host. If necessary, correct any problems before continuing on to the next task.

Log in to the master host as gpadmin:
```
$ su - gpadmin
```
Source the path file from Greenplum Database installation directory:
```
# source /usr/local/greenplum-db/greenplum_path.sh
```
Use the gpssh utility to see if you can login to all hosts without a password prompt, and to confirm that the Greenplum software was installed on all hosts. Use the hostfile_exkeys file you used for installation. For example:
```
$ gpssh -f hostfile_exkeys -e ls -l $GPHOME
```
If the installation was successful, you should be able to log in to all hosts without a password prompt. All hosts should show that they have the same contents in their installation directories, and that the directories are owned by the gpadmin user.

If you are prompted for a password, run the following command to redo the ssh key exchange:
```
$ gpssh-exkeys -f hostfile_exkeys
```