To prepare new host systems for expansion, install the Greenplum Database software binaries, exchange the required SSH keys, and run performance tests.

Run performance tests first on the new hosts and then all hosts. Run the tests on all hosts with the system offline so user activity does not distort results.

Generally, you should run performance tests when an administrator modifies host networking or other special conditions in the system. For example, if you will run the expanded system on two network clusters, run tests on each cluster.

Parent topic: Expanding a Greenplum System

New hosts must exchange SSH keys with the existing hosts to enable Greenplum administrative utilities to connect to all segments without a password prompt. Perform the key exchange process twice with the gpssh-exkeys utility.

  2. To create the gpadmin user

Note

The Greenplum Database segment host naming convention is sdwN where sdw is a prefix and N is an integer ( 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.

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

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

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

    1. # gpssh-exkeys -e /home/gpadmin/<existing_hosts_file> -x 
    2. /home/gpadmin/<new_hosts_file>

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

  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:

    1. # gpssh -f <new_hosts_file> '/usr/sbin/useradd gpadmin -d 
    1. # gpssh -f <new_hosts_file> 'echo <gpadmin_password> | passwd 
    2. gpadmin --stdin'

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

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

    1. # gpssh-exkeys -e /home/gpadmin/<existing_hosts_file> -x 
    2. /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:

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

Use the utility to test disk I/O and memory bandwidth.

  1. 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.