To exchange SSH keys as root

1. Create a host file with the existing host names in your array and a separate host file with the new expansion host names. For existing hosts, you can use the same host file used to set up SSH keys in the system. In the files, list all hosts (master, backup master, and segment hosts) with one name per line and no extra lines or spaces. Exchange SSH keys using the configured host names for a given host if you use a multi-NIC configuration. In this example, mdw is configured with a single NIC, and sdw1, sdw2, and sdw3 are configured with 4 NICs:

   mdw
   sdw1-1
   sdw1-2
   sdw1-3
   sdw1-4
   sdw2-1
   sdw2-2
   sdw2-3
   sdw2-4
   sdw3-1
   sdw3-2
   sdw3-3
   sdw3-4

2. Log in as root on the master host, and source the greenplum_path.sh file from your Greenplum installation.

   $ su - 
   # source /usr/local/greenplum-db/greenplum_path.sh

3. Run the gpssh-exkeys utility referencing the host list files. For example:

   # gpssh-exkeys -f /home/gpadmin/existing_hosts_file -x 
   /home/gpadmin/new_hosts_file

4. gpssh-exkeys checks the remote hosts and performs the key exchange between all hosts. Enter the root user password when prompted. For example:

   ***Enter password for root@hostname: <root_password>

To create the gpadmin user

1. Use gpssh to create the gpadmin user on all the new segment hosts (if it does not exist already). Use the list of new hosts you created for the key exchange. For example:

   # gpssh -f new_hosts_file '/usr/sbin/useradd gpadmin -d 
   /home/gpadmin -s /bin/bash'

2. Set a password for the new gpadmin user. On Linux, you can do this on all segment hosts simultaneously using gpssh. For example:

   # gpssh -f new_hosts_file 'echo gpadmin_password | passwd 
   gpadmin --stdin'

3. Verify the gpadmin user has been created by looking for its home directory:

   # gpssh -f new_hosts_file ls -l /home

To exchange SSH keys as the gpadmin user

1. Log in as gpadmin and run the gpssh-exkeys utility referencing the host list files. For example:

   # gpssh-exkeys -e /home/gpadmin/existing_hosts_file -x 
   /home/gpadmin/new_hosts_file

2. gpssh-exkeys will check the remote hosts and perform the key exchange between all hosts. Enter the gpadmin user password when prompted. For example:

   ***Enter password for gpadmin@hostname: <gpadmin_password>

To run gpcheck

1. Log in on the master host as the user who will run your Greenplum Database system (for example, gpadmin).

   $ su - gpadmin

2. Run the gpcheck utility using your host file for new hosts. For example:

   $ gpcheck -f new_hosts_file

To run gpcheckperf

1. Run the gpcheckperf utility using the host file for new hosts. Use the -d option to specify the file systems you want to test on each host. You must have write access to these directories. For example:

   $ gpcheckperf -f new_hosts_file -d /data1 -d /data2 -v 

2. The utility may take a long time to perform the tests because it is copying very large files between the hosts. When it is finished, you will see the summary results for the Disk Write, Disk Read, and Stream tests.

For a network divided into subnets, repeat this procedure with a separate host file for each subnet.