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Following the release notes for MongoDB you must upgrade to each version of MongoDB along the way.

NOTE: All Linux Commands in this document are run at root level: you need access to root via su or sudo -i

This document will follow the MongoDB upgrade path from 3.4 → 3.6 → 4.0 → 4.2, with the document structured as follows:

1. Prerequisites
2. Upgrade Preparation
3. Upgrade from MongoDB 3.4 to MongoDB 3.6
4. Upgrade from MongoDB 3.6 to MongoDB 4.0
5. Upgrade from MongoDB 4.0 to MongoDB 4.2
6. Services Restart
7. Clean-up

Table of Contents

Prerequisites for Upgrading MongoDB 3.4 to MongoDB 4.2

As MongoDB 3.4 is out of support customers are wanting to upgrade their NMIS installation to newer in support releases. This document outlines the process to bring MongoDB up to version 4.2. There are a series of prerequisites that determine the type of update required. This document outlines the process for MongoDB Standalone.

There are 4 prerequisites to confirm:

• Operating System
• MongoDB Version
• MongoDB Storage Engine
• NMIS and Modules for Mongo 4.2

Supported Operating Systems

MongoDB 3.4 through 4.2 are officially supported on the following Redhat/Centos platforms:

• 6.2+ x64
• 7.0 x64
• 8.0 x64

We have tested the upgrade process on:

• CentOS Linux release 7.9.2009 (Core)

To determine the version of Linux running on your system use the following command in a terminal session:

cat /etc/redhat-release

An example output of this command

CentOS Linux release 7.9.2009 (Core)

MongoDB 3.4 Installed and Running

Verify by running (with your mongodb <username> and <password>)

This command does not do anything however, the output will show us the running shell and server that is running.

mongo -u <username> -p <password> --authenticationDatabase=admin --eval 'quit()' | grep MongoDB

Result will look like below, we are looking for the two version numbers to be 3.4.x

If the versions do not match there may be an issue with your running installation and you should not proceed until this is resolved.

MongoDB shell version v3.4.24
MongoDB server version: 3.4.24

MongoDB Storage Engine

Verify storage engine by running

mongo -u <username> -p <password> --authenticationDatabase=admin --quiet --eval 'db.serverStatus().storageEngine'

The "name" line should have "wiredTiger" in order to proceed.

{
        "name" : "wiredTiger",
        "supportsCommittedReads" : true,
        "readOnly" : false,
        "persistent" : true
}

If this mongo cli command does not work you can try the following to determine the storage engine in use

grep -i "active storage" /var/log/mongodb/mongod.*

Example correct log output - notice the log entry declares the storage engine to be using "wiredTiger"

/var/log/mongodb/mongod.log.1:2022-07-09T01:27:24.052+1000 I  STORAGE  [initandlisten] Detected data files in /var/lib/mongo created by the 'wiredTiger' storage engine, so setting the active storage engine to 'wiredTiger'.

If the system is not using wiredTiger the data migration process should follow a different process. Refer to the following link.

https://www.mongodb.com/docs/v4.2/tutorial/change-standalone-wiredtiger/

Upgrade NMIS and Modules for Mongo 4.2

NMIS and Modules must be updated to versions that support MongoDB v4.2 before upgrading MongoDB to v4.2. These releases are backwards compatible with MongoDB v3.4.

Minimum releases for MongoDB 4.2 are:

• NMIS 9.4.0
• opAddress 2.2.0
• opCharts 4.4.0
• opConfig 4.4.0
• opEvents 4.2.0
• opHA 3.5.0
  

You can determine the versions you are running by browsing to:

https://<yourserveraddress>/omk/

You should follow the standard upgrade process for each of these packages, which is handled by the Opmantek Installer.

Preparation

The preparation phase includes 3 sections

1. System Snapshot/Backup
2. Upgrade to latest stable release packages
3. Shutdown all OMK Daemons

This is to be done in this specific sequence.

System Snapshot/Backup

For System Snapshots and Backups you will need to refer to the documentation for your environment.

If the information on your system, or stability of the system is critical to your business it is important to retain a working backup. It is important that you have confirmed that you backups can be restored.

Options:

• Full system backups, including Operating System and Data - Contact your IT department, Vendor Support, or Integrator
• Virtual Machine Snapshots - Refer to the solution guides for the environment
• Database Dump - MongoDB documentation: https://www.mongodb.com/docs/database-tools/mongodump/

Upgrade Redhat/Centos Packages

After completing the snapshot/backup follow Redhat/Centos instructions for upgrading and checking the sanity of the apt package system.

Community documentation for CentOS/Redhat YUM: https://www.tecmint.com/check-and-install-updates-on-centos-and-rhel/

An example of the update/upgrade cycle is as follows:

yum update -y

This command will execute all outstanding upgrades. Check for any errors and address as required.

Once this step is completed you may optionally reboot the system. This can clear out any memory leaks and instabilities in the system that occur due to long uptimes.

Shutdown All OMK Daemons

Prior to commencing into the MongoDB upgrade cycles it is required to shutdown all OMK processes.

The following commands are used to complete this task

/usr/local/omk/bin/checkomkdaemons.sh stop
systemctl stop nmis9d

These commands offer minimal feedback, confirm that the nmis9d process has halted as follows:

[root@rhnmis9 ~]# systemctl status nmis9d
● nmis9d.service - Opmantek NMIS9 Daemon
   Loaded: loaded (/etc/systemd/system/nmis9d.service; enabled; vendor preset: disabled)
   Active: inactive (dead) since Thu 2022-09-08 17:17:32 AEST; 14s ago
 Main PID: 18086 (code=exited, status=0/SUCCESS)
   CGroup: /system.slice/nmis9d.service

Sep 04 03:31:10 rhnmis9 systemd[1]: Starting Opmantek NMIS9 Daemon...
Sep 04 03:31:13 rhnmis9 systemd[1]: Started Opmantek NMIS9 Daemon.
Sep 08 17:17:31 rhnmis9 systemd[1]: Stopping Opmantek NMIS9 Daemon...
Sep 08 17:17:32 rhnmis9 systemd[1]: Stopped Opmantek NMIS9 Daemon.

Upgrade from MongoDB 3.4 to MongoDB 3.6

Prepare the Database for Upgrade

Check the database compatibility mode is set to "3.4"

mongo -u <YOUR USERNAME> -p <YOUR PASSWORD> --authenticationDatabase=admin --quiet --eval 'db.adminCommand( { getParameter: 1, featureCompatibilityVersion: 1 } )'

The result should be as follows ensuring that the value 3.4 is set

{ "featureCompatibilityVersion" : "3.4", "ok" : 1 }

If MongoDB is on version 3.4 and the featureCompatibilityVersion is not "3.4" then set this with the following command

mongo -u <YOUR USERNAME> -p <YOUR PASSWORD> --authenticationDatabase=admin --quiet --eval 'db.adminCommand( { setFeatureCompatibilityVersion: "3.4" } )';

As before, the check the featureCompatibilityVersion again confirming the correct value

mongo -u <YOUR USERNAME> -p <YOUR PASSWORD> --authenticationDatabase=admin --quiet --eval 'db.adminCommand( { getParameter: 1, featureCompatibilityVersion: 1 } )'

{ "featureCompatibilityVersion" : "3.4", "ok" : 1 }

Redhat/Centos - Install MongoDB 3.6 Repo and Upgrade

Details available here:

https://www.mongodb.com/docs/v3.6/tutorial/install-mongodb-on-red-hat/

Create a new repo file using the follow commands:

echo "[mongodb-org-3.6]" > /etc/yum.repos.d/mongodb-org-3.6.repo
echo "name=MongoDB Repository" >> /etc/yum.repos.d/mongodb-org-3.6.repo
echo "baseurl=https://repo.mongodb.org/yum/redhat/$releasever/mongodb-org/3.6/x86_64/" >> /etc/yum.repos.d/mongodb-org-3.6.repo
echo "gpgcheck=1" >> /etc/yum.repos.d/mongodb-org-3.6.repo
echo "enabled=1" >> /etc/yum.repos.d/mongodb-org-3.6.repo
echo "gpgkey=https://www.mongodb.org/static/pgp/server-3.6.asc" >> /etc/yum.repos.d/mongodb-org-3.6.repo

Upgrading the installation is as follows:

sudo yum update -y mongodb-org
systemctl stop mongod
systemctl start mongod
systemctl daemon-reload
systemctl is-active mongod

Complete the upgrade with the following commands and retest. If you skip the stop/start sequence above the following command will fail.

mongo -u <YOUR USERNAME> -p <YOUR PASSWORD> --authenticationDatabase=admin --quiet --eval 'db.adminCommand( { setFeatureCompatibilityVersion: "3.6" } )'
mongo -u <YOUR USERNAME> -p <YOUR PASSWORD> --authenticationDatabase=admin --quiet --eval 'db.adminCommand( { getParameter: 1, featureCompatibilityVersion: 1 } )'
systemctl stop mongod
systemctl start mongod

Upgrade from MongoDB 3.6 to MongoDB 4.0

Prepare the Database for Upgrade

Check the database compatibility mode is set to "3.6"

mongo -u <YOUR USERNAME> -p <YOUR PASSWORD> --authenticationDatabase=admin --quiet --eval 'db.adminCommand( { getParameter: 1, featureCompatibilityVersion: 1 } )'

The result should be as follows ensuring that the value 3.6 is set

{ "featureCompatibilityVersion" : "3.6", "ok" : 1 }

If MongoDB is on version 3.6 and the featureCompatibilityVersion is not "3.6" then set this with the following command

mongo -u <YOUR USERNAME> -p <YOUR PASSWORD> --authenticationDatabase=admin --quiet --eval 'db.adminCommand( { setFeatureCompatibilityVersion: "3.6" } )';

As before, the check the featureCompatibilityVersion again confirming the correct value

mongo -u <YOUR USERNAME> -p <YOUR PASSWORD> --authenticationDatabase=admin --quiet --eval 'db.adminCommand( { getParameter: 1, featureCompatibilityVersion: 1 } )'

{ "featureCompatibilityVersion" : "3.6", "ok" : 1 }

Redhat/Centos - Install MongoDB 4.0 Repo and Upgrade

Details available here:

https://www.mongodb.com/docs/v4.0/tutorial/install-mongodb-on-red-hat/

Create a new repo file using the follow commands:

echo "[mongodb-org-4.0]" > /etc/yum.repos.d/mongodb-org-4.0.repo
echo "name=MongoDB Repository" >> /etc/yum.repos.d/mongodb-org-4.0.repo
echo "baseurl=https://repo.mongodb.org/yum/redhat/$releasever/mongodb-org/4.0/x86_64/" >> /etc/yum.repos.d/mongodb-org-4.0.repo
echo "gpgcheck=1" >> /etc/yum.repos.d/mongodb-org-4.0.repo
echo "enabled=1" >> /etc/yum.repos.d/mongodb-org-4.0.repo
echo "gpgkey=https://www.mongodb.org/static/pgp/server-4.0.asc" >> /etc/yum.repos.d/mongodb-org-4.0.repo

Upgrading the installation is as follows:

sudo yum update -y mongodb-org
systemctl stop mongod
systemctl start mongod
systemctl daemon-reload
systemctl is-active mongod

Complete the upgrade with the following commands and retest. If you skip the stop/start sequence above the following command will fail.

mongo -u <YOUR USERNAME> -p <YOUR PASSWORD> --authenticationDatabase=admin --quiet --eval 'db.adminCommand( { setFeatureCompatibilityVersion: "4.0" } )'
mongo -u <YOUR USERNAME> -p <YOUR PASSWORD> --authenticationDatabase=admin --quiet --eval 'db.adminCommand( { getParameter: 1, featureCompatibilityVersion: 1 } )'
systemctl stop mongod
systemctl start mongod

As before, check the featureCompatibilityVersion output from above is "4.0"

mongo -u <YOUR USERNAME> -p <YOUR PASSWORD> --authenticationDatabase=admin --quiet --eval 'db.adminCommand( { getParameter: 1, featureCompatibilityVersion: 1 } )'

{ "featureCompatibilityVersion" : "4.0", "ok" : 1 }

Upgrade from MongoDB 4.0 to MongoDB 4.2

Prepare the Database for Upgrade

Check the database compatibility mode is set to "4.0"

mongo -u <YOUR USERNAME> -p <YOUR PASSWORD> --authenticationDatabase=admin --quiet --eval 'db.adminCommand( { getParameter: 1, featureCompatibilityVersion: 1 } )'

The result should be as follows ensuring that the value 4.0 is set

{ "featureCompatibilityVersion" : "4.0", "ok" : 1 }

If MongoDB is on version 4.0 and the featureCompatibilityVersion is not "4.0" then set this with the following command

mongo -u <YOUR USERNAME> -p <YOUR PASSWORD> --authenticationDatabase=admin --quiet --eval 'db.adminCommand( { setFeatureCompatibilityVersion: "4.0" } )';

As before, the check the featureCompatibilityVersion again confirming the correct value

mongo -u <YOUR USERNAME> -p <YOUR PASSWORD> --authenticationDatabase=admin --quiet --eval 'db.adminCommand( { getParameter: 1, featureCompatibilityVersion: 1 } )'

{ "featureCompatibilityVersion" : "4.0", "ok" : 1 }

Redhat/Centos - Install MongoDB 4.2 Repo and Upgrade

Details available here:

https://www.mongodb.com/docs/v4.2/tutorial/install-mongodb-on-red-hat/

Create a new repo file using the follow commands:

echo "[mongodb-org-4.2]" > /etc/yum.repos.d/mongodb-org-4.2.repo
echo "name=MongoDB Repository" >> /etc/yum.repos.d/mongodb-org-4.2.repo
echo "baseurl=https://repo.mongodb.org/yum/redhat/$releasever/mongodb-org/4.2/x86_64/" >> /etc/yum.repos.d/mongodb-org-4.2.repo
echo "gpgcheck=1" >> /etc/yum.repos.d/mongodb-org-4.2.repo
echo "enabled=1" >> /etc/yum.repos.d/mongodb-org-4.2.repo
echo "gpgkey=https://www.mongodb.org/static/pgp/server-4.2.asc" >> /etc/yum.repos.d/mongodb-org-4.2.repo

Upgrading the installation is as follows:

sudo yum update -y mongodb-org
systemctl stop mongod
systemctl start mongod
systemctl daemon-reload
systemctl is-active mongod

Complete the upgrade with the following commands and retest. If you skip the stop/start sequence above the following command will fail.

mongo -u <YOUR USERNAME> -p <YOUR PASSWORD> --authenticationDatabase=admin --quiet --eval 'db.adminCommand( { setFeatureCompatibilityVersion: "4.2" } )'
mongo -u <YOUR USERNAME> -p <YOUR PASSWORD> --authenticationDatabase=admin --quiet --eval 'db.adminCommand( { getParameter: 1, featureCompatibilityVersion: 1 } )'
systemctl stop mongod
systemctl start mongod

As before, check the featureCompatibilityVersion output from above is "4.2"

mongo -u <YOUR USERNAME> -p <YOUR PASSWORD> --authenticationDatabase=admin --quiet --eval 'db.adminCommand( { getParameter: 1, featureCompatibilityVersion: 1 } )'

{ "featureCompatibilityVersion" : "4.2", "ok" : 1 }

This completes the in-situ upgrade of MongoDB 3.4 to 4.2 Standalone

Restart All OMK Daemons

Now the MongoDB upgrade is complete, you can start all the NMIS and OMK processes.

The following commands are used to complete this task

/usr/local/omk/bin/checkomkdaemons.sh start
systemctl start nmis9d

You can now browse to your instance of NMIS:

https://<yourserver>/omk

You will get a screen similar to the following which will give you a status on all installed services:

Image Added