Verify your new host systems are ready for integration into the existing Greenplum system.
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.
NotePreparing host systems for use by a Greenplum Database system assumes that the new hosts' operating system has been properly configured to match the existing hosts, described in Configuring Your Systems.
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.
First perform the process as root
, for administration convenience, and then as the user gpadmin
, for management utilities. Perform the following tasks in order:
NoteThe Greenplum Database segment host naming convention is
sdwN
wheresdw
is a prefix andN
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
andsdw1-2
are the two interface names for hostsdw1
.
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
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
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>
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>
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'
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'
Verify the gpadmin
user has been created by looking for its home directory:
# gpssh -f <new_hosts_file> ls -l /home
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>
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>
Use the gpcheckperf utility to test disk I/O and memory bandwidth.
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
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.
Before initializing the system with the new segments, shut down the system with gpstop
to prevent user activity from skewing performance test results. Then, repeat the performance tests using host files that include all hosts, existing and new.