Upgrading my standalone non-sharded MongoDB systems, each running v3.2.8, to v3.4.6

Reference: https://www.mongodb.com/docs/manual/release-notes/3.4-upgrade-standalone/
My mongodb systems are running under CentOS-7 and their only clients are Java apps which pull from v3.2.8 AND also v3.4.6 MongoDB databases. The MongoDB servers are AWS EC2s and are NOT clustered.

Is it really as simple as this:

  1. Stop MongoDB
    systemctl stop mongodb.service
  2. Replace existing 3.2 binaries with 3.4 binaries
    sudo su -
    mv /App/mongodb/bin /App/mongodb/bin3.2.8
    cp -pr /App/mongodb/bin3.4.6 /App/mongodb/bin
  3. Start MongoDB
    systemctl start mongodb.service
  4. Enable backwards-incompatible 3.4 features
    /App/mongodb/bin/mongo --quiet --eval ‘db.adminCommand( { setFeatureCompatibilityVersion: “3.4” } )’

Do I need to make any changes to the data or metadata for my data? Anything at all?
Should I stop my EC2s, snapshot the drive where MongoDB has all its data, and then start the EC2s and start up my MongoDB databases as a first step? I will if there is ANY chance I’ll need to backout the upgrade because something “goes wrong”.

Welcome to the MongoDB Community @Joseph_Estrada !

The 3.2 to 3.4 upgrade procedure is as per the documentation link you referenced.

While this is a straightforward upgrade, I would always take a backup before any significant deployment changes.

I also recommend upgrading to the latest patch release for your release series, which would be 3.4.24. Minor releases do not include any backward-breaking changes and 3.4.6 (July 2017) is lacking 2 1/2 years of bug fixes & stability improvements compared to 3.4.24 (Jan 2020).

MongoDB 3.4 reached End of Life in Jan 2020 and no longer receives any security updates or maintenance support. I recommend planning to upgrade to a supported version (currently 4.2 or newer) if this is a production environment.