Initializing a SynxDB System

Describes how to initialize a SynxDB database system.

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

This chapter contains the following topics:

Overview
Initializing SynxDB
Setting SynxDB Environment Variables
Next Steps

Overview

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

Each database instance (the master 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. SynxDB provides its own version of initdb called gpinitsystem, which takes care of initializing the database on the master and on each segment instance, and starting each instance in the correct order.

After the SynxDB 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 SynxDB master.

Initializing SynxDB

These are the high-level tasks for initializing SynxDB:

Make sure you have completed all of the installation tasks described in Configuring Your Systems and Installing the SynxDB Software.
Create a host file that contains the host addresses of your segments. See Creating the Initialization Host File.
Create your SynxDB system configuration file. See Creating the SynxDB Configuration File.
By default, SynxDB will be initialized using the locale of the master 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.
Run the SynxDB initialization utility on the master host. See Running the Initialization Utility.
Set the SynxDB timezone. See Setting the SynxDB Timezone.
Set environment variables for the SynxDB user. See Setting SynxDB Environment Variables.

When performing the following initialization tasks, you must be logged into the master host as the gpadmin user, and to run SynxDB utilities, you must source the synxdb_path.sh file to set SynxDB environment variables. For example, if you are logged into the master, run these commands.

$ su - gpadmin
$ source /usr/local/synxdb/synxdb_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 master or standby master). For segment machines with multiple, unbonded network interfaces, this file should list the host address names for each interface — one per line.

Note The SynxDB 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

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
```
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 SynxDB Configuration File

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

To create a gpinitsystem_config file

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

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 SynxDB system must contain a master 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=mdw 
MASTER_DIRECTORY=/data/master 
MASTER_PORT=5432 
TRUSTED SHELL=ssh
CHECK_POINT_SEGMENTS=8
ENCODING=UNICODE
```
(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 SynxDB system with primary segments only and deploy mirrors later using the gpaddmirrors utility.
Save and close the file.

Running the Initialization Utility

The gpinitsystem utility will create a SynxDB system using the values defined in the configuration file.

These steps assume you are logged in as the gpadmin user and have sourced the synxdb_path.sh file to set SynxDB environment variables.

To run the initialization utility

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 master 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_master_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 SynxDB system; it merely generates and saves a file with cluster configuration details.
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 SynxDB creation? Yy/Nn
```
Press y to start the initialization.
The utility will then begin setup and initialization of the master 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.
At the end of a successful setup, the utility will start your SynxDB system. You should see:
```
=> SynxDB 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 ~/gpAdminLogs.

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:

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

You can use this script to clean up a partially created SynxDB 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 SynxDB array.

The following example shows how to run the backout script:

$ bash ~/gpAdminLogs/backout_gpinitsystem_gpadmin_20071031_121053

Setting the SynxDB Timezone

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

Use the gpconfig utility to show and set the SynxDB timezone. For example, these commands show the SynxDB timezone and set the timezone to US/Pacific.

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

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

For more information about the SynxDB timezone, see Configuring Timezone and Localization Settings.

Setting SynxDB Environment Variables

You must set environment variables in the SynxDB user (gpadmin) environment that runs SynxDB on the SynxDB master and standby master hosts. A synxdb_path.sh file is provided in the SynxDB installation directory with environment variable settings for SynxDB.

The SynxDB 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 master data directory location.

Note The synxdb_path.sh script changes the operating environment in order to support running the SynxDB-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 SynxDB

Open the gpadmin profile file (such as .bashrc) in a text editor. For example:
```
$ vi ~/.bashrc
```
Add lines to this file to source the synxdb_path.sh file and set the MASTER_DATA_DIRECTORY environment variable. For example:
```
source /usr/local/synxdb/synxdb_path.sh
export MASTER_DATA_DIRECTORY=/data/master/gpseg-1
```
(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
```
(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 synxdb_path.sh environment:
```
export LD_PRELOAD=/lib64/libz.so.1 ps
```
Save and close the file.
After editing the profile file, source it to make the changes active. For example:
```
$ source ~/.bashrc
```
If you have a standby master host, copy your environment file to the standby master 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
Creating Databases and Loading Data

Allowing Client Connections

After a SynxDB 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 SynxDB, you must give them access. See the SynxDB 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 SynxDB Administrator Guide for more information about creating databases, schemas, tables, and other database objects in SynxDB and loading your data.

SynxDB 2 Documentation