Initializing a LightDB-A Database System

Describes how to initialize a LightDB-A Database database system.

The instructions in this chapter assume you have already prepared your hosts as described in Configuring Your Systems and installed the LightDB-A Database software on all of the hosts in the system according to the instructions in Installing the LightDB-A Database Software.

This chapter contains the following topics:

Parent topic: Installing and Upgrading LightDB-A

Overview

Because LightDB-A Database is distributed, the process for initializing a LightDB-A Database management system (DBMS) involves initializing several individual PostgreSQL database instances (called segment instances in LightDB-A).

Each database instance (the coordinator and all segments) must be initialized across all of the hosts in the system in such a way that they can all work together as a unified DBMS. LightDB-A provides its own version of initdb called gpinitsystem, which takes care of initializing the database on the coordinator and on each segment instance, and starting each instance in the correct order.

After the LightDB-A Database database system has been initialized and started, you can then create and manage databases as you would in a regular PostgreSQL DBMS by connecting to the LightDB-A coordinator.

Initializing LightDB-A Database

These are the high-level tasks for initializing LightDB-A Database:

  1. Make sure you have completed all of the installation tasks described in Configuring Your Systems and Installing the LightDB-A Database Software.
  2. Create a host file that contains the host addresses of your segments. See Creating the Initialization Host File.
  3. Create your LightDB-A Database system configuration file. See Creating the LightDB-A Database Configuration File.
  4. By default, LightDB-A Database will be initialized using the locale of the coordinator host system. Make sure this is the correct locale you want to use, as some locale options cannot be changed after initialization. See Configuring Timezone and Localization Settings for more information.
  5. Run the LightDB-A Database initialization utility on the coordinator host. See Running the Initialization Utility.
  6. Set the LightDB-A Database timezone. See Setting the LightDB-A Database Timezone.
  7. Set environment variables for the LightDB-A Database user. See Setting LightDB-A Environment Variables.

When performing the following initialization tasks, you must be logged into the coordinator host as the gpadmin user, and to run LightDB-A Database utilities, you must source the lightdb_a_path.sh file to set LightDB-A Database environment variables. For example, if you are logged into the coordinator, run these commands.

$ su - gpadmin
$ source /usr/local/greenplum-db/lightdb_a_path.sh

Creating the Initialization Host File

The gpinitsystem utility requires a host file that contains the list of addresses for each segment host. The initialization utility determines the number of segment instances per host by the number host addresses listed per host times the number of data directory locations specified in the gpinitsystem_config file.

This file should only contain segment host addresses (not the coordinator or standby coordinator). For segment machines with multiple, unbonded network interfaces, this file should list the host address names for each interface — one per line.

Note The LightDB-A Database segment host naming convention is sdwN where sdw is a prefix and N is an integer. For example, sdw2 and so on. If hosts have multiple unbonded NICs, 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. However, NIC bonding is recommended to create a load-balanced, fault-tolerant network.

To create the initialization host file

  1. Create a file named hostfile_gpinitsystem. In this file add the host address name(s) of your segment host interfaces, one name per line, no extra lines or spaces. For example, if you have four segment hosts with two unbonded network interfaces each:

    sdw1-1
sdw1-2
sdw2-1
sdw2-2
sdw3-1
sdw3-2
sdw4-1
sdw4-2

  2. Save and close the file.

Note If you are not sure of the host names and/or interface address names used by your machines, look in the /etc/hosts file.

Creating the LightDB-A Database Configuration File

Your LightDB-A Database configuration file tells the gpinitsystem utility how you want to configure your LightDB-A Database system. An example configuration file can be found in $GPHOME/docs/cli_help/gpconfigs/gpinitsystem_config.

To create a gpinitsystem_config file

  1. Make a copy of the gpinitsystem_config file to use as a starting point. For example:

    $ cp $GPHOME/docs/cli_help/gpconfigs/gpinitsystem_config \
     /home/gpadmin/gpconfigs/gpinitsystem_config

  2. Open the file you just copied in a text editor.

    Set all of the required parameters according to your environment. See gpinitsystem for more information. A LightDB-A Database system must contain a coordinator instance and at least two segment instances (even if setting up a single node system).

    The DATA_DIRECTORY parameter is what determines how many segments per host will be created. If your segment hosts have multiple network interfaces, and you used their interface address names in your host file, the number of segments will be evenly spread over the number of available interfaces.

    To specify PORT_BASE, review the port range specified in the net.ipv4.ip_local_port_range parameter in the /etc/sysctl.conf file. See Recommended OS Parameters Settings.

    Here is an example of the required parameters in the gpinitsystem_config file:

    SEG_PREFIX=gpseg
PORT_BASE=6000 
declare -a DATA_DIRECTORY=(/data1/primary /data1/primary /data1/primary /data2/primary /data2/primary /data2/primary)
MASTER_HOSTNAME=cdw 
MASTER_DIRECTORY=/data/coordinator 
MASTER_PORT=5432 
TRUSTED SHELL=ssh
CHECK_POINT_SEGMENTS=8
ENCODING=UNICODE

  3. (Optional) If you want to deploy mirror segments, uncomment and set the mirroring parameters according to your environment. To specify MIRROR_PORT_BASE, review the port range specified under the net.ipv4.ip_local_port_range parameter in the /etc/sysctl.conf file. Here is an example of the optional mirror parameters in the gpinitsystem_config file:

    MIRROR_PORT_BASE=7000
declare -a MIRROR_DATA_DIRECTORY=(/data1/mirror /data1/mirror /data1/mirror /data2/mirror /data2/mirror /data2/mirror)

    Note You can initialize your LightDB-A system with primary segments only and deploy mirrors later using the gpaddmirrors utility.

  4. Save and close the file.

Running the Initialization Utility

The gpinitsystem utility will create a LightDB-A Database system using the values defined in the configuration file.

These steps assume you are logged in as the gpadmin user and have sourced the lightdb_a_path.sh file to set LightDB-A Database environment variables.

To run the initialization utility

  1. Run the following command referencing the path and file name of your initialization configuration file (gpinitsystem_config) and host file (hostfile_gpinitsystem). For example:

    $ cd ~
$ gpinitsystem -c gpconfigs/gpinitsystem_config -h gpconfigs/hostfile_gpinitsystem

    For a fully redundant system (with a standby coordinator and a spread mirror configuration) include the -s and --mirror-mode=spread options. For example:

    $ gpinitsystem -c gpconfigs/gpinitsystem_config -h gpconfigs/hostfile_gpinitsystem \
  -s <standby_coordinator_hostname> --mirror-mode=spread

    During a new cluster creation, you may use the -O output\_configuration\_file option to save the cluster configuration details in a file. For example:

    $ gpinitsystem -c gpconfigs/gpinitsystem_config -O gpconfigs/config_template

    This output file can be edited and used at a later stage as the input file of the -I option, to create a new cluster or to recover from a backup. See gpinitsystem for further details.

    Note Calling gpinitsystem with the -O option does not initialize the LightDB-A Database system; it merely generates and saves a file with cluster configuration details.

  2. The utility will verify your setup information and make sure it can connect to each host and access the data directories specified in your configuration. If all of the pre-checks are successful, the utility will prompt you to confirm your configuration. For example:

    => Continue with LightDB-A creation? Yy/Nn

  3. Press y to start the initialization.

  4. The utility will then begin setup and initialization of the coordinator instance and each segment instance in the system. Each segment instance is set up in parallel. Depending on the number of segments, this process can take a while.

  5. At the end of a successful setup, the utility will start your LightDB-A Database system. You should see:

    => LightDB-A Database instance successfully created.

Troubleshooting Initialization Problems

If the utility encounters any errors while setting up an instance, the entire process will fail, and could possibly leave you with a partially created system. Refer to the error messages and logs to determine the cause of the failure and where in the process the failure occurred. Log files are created in ~/ltaAdminLogs.

Depending on when the error occurred in the process, you may need to clean up and then try the gpinitsystem utility again. For example, if some segment instances were created and some failed, you may need to stop postgres processes and remove any utility-created data directories from your data storage area(s). A backout script is created to help with this cleanup if necessary.

Using the Backout Script

If the gpinitsystem utility fails, it will create the following backout script if it has left your system in a partially installed state:

~/ltaAdminLogs/backout_gpinitsystem_<user>_<timestamp>

You can use this script to clean up a partially created LightDB-A Database system. This backout script will remove any utility-created data directories, postgres processes, and log files. After correcting the error that caused gpinitsystem to fail and running the backout script, you should be ready to retry initializing your LightDB-A Database array.

The following example shows how to run the backout script:

$ bash ~/ltaAdminLogs/backout_gpinitsystem_gpadmin_20071031_121053

Setting the LightDB-A Database Timezone

As a best practice, configure LightDB-A Database and the host systems to use a known, supported timezone. LightDB-A Database uses a timezone from a set of internally stored PostgreSQL timezones. Setting the LightDB-A Database timezone prevents LightDB-A Database from selecting a timezone each time the cluster is restarted and sets the timezone for the LightDB-A Database coordinator and segment instances.

Use the gpconfig utility to show and set the LightDB-A Database timezone. For example, these commands show the LightDB-A Database timezone and set the timezone to US/Pacific.

$ gpconfig -s TimeZone
$ gpconfig -c TimeZone -v 'US/Pacific'

You must restart LightDB-A Database after changing the timezone. The command gpstop -ra restarts LightDB-A Database. The catalog view pg_timezone_names provides LightDB-A Database timezone information.

For more information about the LightDB-A Database timezone, see Configuring Timezone and Localization Settings.

Setting LightDB-A Environment Variables

You must set environment variables in the LightDB-A Database user (gpadmin) environment that runs LightDB-A Database on the LightDB-A Database coordinator and standby coordinator hosts. A lightdb_a_path.sh file is provided in the LightDB-A Database installation directory with environment variable settings for LightDB-A Database.

The LightDB-A Database management utilities also require that the MASTER_DATA_DIRECTORY environment variable be set. This should point to the directory created by the gpinitsystem utility in the coordinator data directory location.

Note The lightdb_a_path.sh script changes the operating environment in order to support running the LightDB-A Database-specific utilities. These same changes to the environment can negatively affect the operation of other system-level utilities, such as ps or yum. Use separate accounts for performing system administration and database administration, instead of attempting to perform both functions as gpadmin.

These steps ensure that the environment variables are set for the gpadmin user after a system reboot.

To set up the gpadmin environment for LightDB-A Database

  1. Open the gpadmin profile file (such as .bashrc) in a text editor. For example:

    $ vi ~/.bashrc

  2. Add lines to this file to source the lightdb_a_path.sh file and set the MASTER_DATA_DIRECTORY environment variable. For example:

    source /usr/local/greenplum-db/lightdb_a_path.sh
export MASTER_DATA_DIRECTORY=/data/coordinator/gpseg-1

  3. (Optional) You may also want to set some client session environment variables such as PGPORT, PGUSER and PGDATABASE for convenience. For example:

    export PGPORT=5432
export PGUSER=gpadmin
export PGDATABASE=gpadmin

  4. (Optional) If you use RHEL 7 or CentOS 7, add the following line to the end of the .bashrc file to enable using the ps command in the lightdb_a_path.sh environment:

    export LD_PRELOAD=/lib64/libz.so.1 ps

  5. Save and close the file.

  6. After editing the profile file, source it to make the changes active. For example:

    $ source ~/.bashrc

  7. If you have a standby coordinator host, copy your environment file to the standby coordinator as well. For example:

    $ cd ~
$ scp .bashrc <standby_hostname>:`pwd`

Note The .bashrc file should not produce any output. If you wish to have a message display to users upon logging in, use the .bash_profile file instead.

Next Steps

After your system is up and running, the next steps are:

Allowing Client Connections

After a LightDB-A Database is first initialized it will only allow local connections to the database from the gpadmin role (or whatever system user ran gpinitsystem). If you would like other users or client machines to be able to connect to LightDB-A Database, you must give them access. See the LightDB-A Database Administrator Guide for more information.

Creating Databases and Loading Data

After verifying your installation, you may want to begin creating databases and loading data. See Defining Database Objects and Loading and Unloading Data in the LightDB-A Database Administrator Guide for more information about creating databases, schemas, tables, and other database objects in LightDB-A Database and loading your data.