1. Pre-installation requirements

ThingWorx High Availability > Example Deployment of PostgreSQL HA with Pgpool-II > 1. Pre-installation requirements

All pre-installation steps should be performed on all PostgreSQL nodes.

Network Communication

All three PostgreSQL nodes need to communicate with each other via TCP for WAL (write ahead of log).

row	Port	Purpose
1	5432	This port is used for PostgreSQL communication.
2	22	This SSH port will be used for Pgpool to invoke scripts on PostgreSQL nodes.
3	NFS?	All PostgreSQL nodes must have access to a common file share location to write and access archive logs. This port may vary depending on the chosen file sharing method

File Sharing

Each PostgreSQL node must have a unique shared location where it can write its archive logs and the other nodes can access them.

row	Folder Name	Purpose
1	/db/node0archive	node0 will write the archive log to this folder and the follower will read from it. this folder will be shared across node0, node1 and node2.
2	/db/node1archive	node1 will write the archive log to this folder and the follower will read from it. this folder will be shared across node0, node1 and node2.
3	/db/node2archive	node2 will write the archive log to this folder and the follower will read from it. this folder will be shared across node0, node1 and node2.

Remote Access

Each Pgpool node requires SSH access without providing a password to all PostgreSQL nodes. The Pgpool user should be trusted by the PostgreSQL nodes.

Configuring this trust relationship is not be covered by this example.

Database Folder Setup

Postgresql 10 will by default install into /var/lib/postgresql/10.x/main and /var/lib/postgresql/10.x/data. However, in this example all installations are directed to /db/ to reflect a common production practice where data files are not maintained on an operating system disk.

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