Replication Setup and Configuration Guide

1. Software Installation

1.1 Download Software

Download the required software onto each server.

1.2 Install Software

IMPORTANT : All the servers should be setup with the following

a. Pollers and mirrors discovered by the Main-Primary

b. Server names set

c. Secondary Primary server setup as Primary

c. One server needs to be an Arbiter. A poller can be used for this

c. Mongo 6 installed

In this setup guide we are using example server/host names so you will have to use the names that you have set for your own configuration. For this example we have the required 6 servers for the setup.

Main-Primary Server : opha-dev1.opmantek.net

Poller1 Server opha-dev2.opmantek.net [Arbiter Server]

Mirror1 Server opha-dev3.opmantek.net

Poller2 Server opha-dev4.opmantek.net

Mirror2 Server opha-dev5.opmantek.net

Second-Primary opha-dev6.opmantek.net

Run the installation commands on each server as needed.

All the following setup commands in this setup should be run as the root user

sh ./opHA-Linux-x86_64-5.0.0.run

VERY IMPORTANT : During the installation of the arbiter server you must answer 'N' at the following prompt

2. NATS Setup

This configuration should be applied to the Main-Primary, Arbiter, and Secondary Primary servers ONLY.

Edit Configuration: Update the /etc/nats-server.conf file with the following settings:

server_name: "opha-dev1.opmantek.net"  #The local server  
http_port: 8222 
listen: 4222 
jetstream: enabled 
accounts { 
  $SYS { 
    users = [ 
      { user: "admin",
        pass: "password" 
      } 
    ] 
  } 
  ophad: { 
    users: [ 
        { user: "omkadmin", password: "op42opha42" } 
    ] 
    jetstream: enabled 
  } 
} 

jetstream { 
  store_dir: "/opt/nats/storage" 
  max_memory_store: 1028M 
  max_file_store: 1028M 
} 
cluster { 
  name: "C1" 
  host: "opha-dev1.opmantek.net"  #The current host 
  # the current server 
  listen: "0.0.0.0:6222" 
  routes: [ 
    # secondary primary
    "nats://opha-dev6.opmantek.net:6222", 
    # server with the arbiter 
    "nats://opha-dev2.opmantek.net:6222" 
    # other servers 
  ] 
}

3. Common Configuration for All Servers

3.1 Update `/usr/local/omk/conf/opCommon.json`

Backup Configuration: Make a backup copy of the opCommon.json file before making any changes.
Add NATS Cluster Configuration: Ensure the following configuration is included in opCommon.json on all servers. In the below example we have added the main-primary, arbiter and second-primary in the nats_cluster array under the “database“ json object
```
"nats_cluster": [ "opha-dev1.opmantek.net:4222", "opha-dev2.opmantek.net:4222", "opha-dev6.opmantek.net:4222" ]
```

4. Server-Specific Configuration

4.1 Update `/usr/local/omk/conf/opCommon.json` for Main-Primary and Secondary Primary only

and Secondary Primary servers:

"db_replica_set": "rs1", 
"db_mongo_cluster": [ "opha-dev1.opmantek.net", "opha-dev6.opmantek.net" ], 
"nats_num_replicas": 3, 
"nats_cluster": [ "opha-dev1.opmantek.net", "opha-dev2.opmantek.net", "opha-dev6.opmantek.net" ]

4.2 Update `opLicense.json`

Make any necessary updates to opLicense.json as required by your licensing terms.

Currently there are 2 available licenses and messagebus will not run without a license.

opHA-MB for NMIS & opCharts (This license is required for messagebus to run)
opHA-MB for opEvents (This license is an add-on for opEvents)

5. MongoDB Setup (Main-Primary Only)

The following steps should be performed only on the Main-Primary MongoDB instance.

5.1 Initialize MongoDB Replica Set

Connect to MongoDB using the mongosh command and configure the replica set:

Run the following command

mongosh --username opUserRW --password op42flow42 admin

Run the following command

rs.initiate({ _id: "rs1", version: 1, members: [ { _id: 0, host : "opha-dev1.opmantek.net:27017" }, { _id: 1, host : "opha-dev6.opmantek.net:27017" } ] })

5.2 Set Default Write Concern

Run the following command to set the default write concern:

db.adminCommand({ "setDefaultRWConcern": 1, "defaultWriteConcern": { "w": 1 } })

5.3 Add Arbiter

Run the following command to add an arbiter to the replica set:

rs.addArb("opha-dev2.opmantek.net:27018")

5.4 Restart mongod on the Main-Primary and Second-Primary

Run the following command on the Main-Primary, Secondary Primary, and Arbiter servers ONLY:

sudo systemctl restart mongod

6. Starting Services

6.1 Start NATS

Start the NATS service on the Main-Primary, Secondary Primary, and Arbiter servers ONLY:

systemctl start nats-server

6.2 Restart mongod on Pollers and Mirrors only

After configuration changes, restart mongod on all Mirrors and Pollers servers ONLY :

systemctl restart mongod

6.3 Restart services on all servers

After configuration changes, restart the services on all the servers :

systemctl restart nmis9d opchartsd opeventsd omkd ophad

6.4 Start the Poller and Mirrors

Execute the following command on the poller and mirror servers.

cd /usr/local/omk/bin
./ophad cmd producer start

7. Final Steps

Accept EULAs: Make sure when you login to each server to confirm that all End User License Agreements (EULAs) are accepted.

8. Switching Main and Secondary Primary Servers

To switch from Main-Primary to Secondary Primary, follow these steps:

Connect to MongoDB:

mongosh --username opUserRW --password op42flow42 admin

Update member priorities:

cfg = rs.conf()
cfg.members[0].priority = 0.6
cfg.members[1].priority = 0.5
rs.reconfig(cfg)

opHA 5 Installation