During this talk, we'll navigate through a customer's journey as they migrate an existing MongoDB deployment to MongoDB Atlas. While the migration itself tends to be only a few clicks, the prep/post effort requires due diligence to ensure a smooth transfer. We'll cover these steps in detail and provide best practices. Whenever you're ready to migrate, you'll be equipped with the confidence, advice, and resources to assist you during every single step along the way.

2. Best Practices for Migrating to
MongoDB Atlas
Diana | Sr Consulting Engineer | MongoDB

3. “To free the genius within
everyone by making data
ridiculously easy to work
with.”

4. Agenda
Why Atlas?
Prep Items
The Migration
Post steps
Queries & Answers

5. Why Atlas?

6. Why Atlas?
Atlas
MongoDB as a Service
Cloud Agnostic
GCP
AWS
Azure
Secure By Default
IP Whitelisting
LDAP
Encrypted Backups
TLS
Values
Self Service Database Access
Best Practices From Day 1
Drives Focus To Development
https://www.mongodb.com/cloud/atlas

7. Prep Items

8. Prep Items
> db.getReplicationInfo()
Gather details about existing cluster
Launch new Atlas Cluster
Working set in RAM
Resize OpLog❗
Check version compatibility, including your drivers❗

9. Prep Items
use admin
db.createUser({
user: "migrationSourceUser",
pwd: "pass",
roles: [ "clusterMonitor", "readAnyDatabase" ]
})
Create Users
IP Whitelist your apps
Verify apps can talk to Atlas❗

10. Prep Items mgeneratejs '{
"_id": "$objectid",
"dateTime": "$date",
"createdAt": "$date",
"Action" :"$string",
"severityLevel": "$integer",
"source": "$string",
"display": "$string",
"deviceServerIp": "$ip",
"details": {
"ipAddress": "$ip",
"macAddress": "$string",
"userId": "SYSTEM",
"method": "method"
}}' --jsonArray -n 234553518 |
mongoimport --jsonArray --port 27017 --
upsert -d atlas -c iot
Test, Test, Test ❗
Identify Maintenance Window
Simulate Production Traffic
POCDriver
> https://github.com/johnlpage/POCDriver
npm install -g mgeneratejs
> https://github.com/rueckstiess/mgeneratejs

11. The Migration
Visit our MongoDB Docs
> https://docs.atlas.mongodb.com/import/

12. Comparing Options
Live Migrate ✅✅✅ mongomirror mongodump|mongorestore
RS or Sharded RS only All deployments
Great for most customers Can avoid network hop Downtime proportional to data size
Short cutover window
Built-in Atlas UI
User-controlled cut-over Sharded -> RS

13. Behind The Scenes
1. initial sync, copying documents and
building indexes that already exist on
the source deployment.
2. oplog sync, tailing and applying
entries from the oplog.

14. Live Migrate
Atlas-Integrated
Validates Prereqs
Starts Migration and shows progress

15. Live Migrate

16. Live Migrate
Restart apps pointing to your NEW cluster❗

17. mongomirror
Start Migration
Monitor Logs or HTTP GET
User-controlled cutover
Stop write traffic
details.currentTimestamp == details.latestTimestamp
Restart apps pointing to your NEW cluster
nohup bin/mongomirror --host=my-source-
replica/ec2-54-193-76-97.us-west-
1.compute.amazonaws.com:27017 --
destination atlasfreedom-shard-
0/atlasfreedom-shard-00-00-
tzosc.gcp.mongodb.net:27017,atlasfreedom-
shard-00-01-
tzosc.gcp.mongodb.net:27017,atlasfreedom-
shard-00-02-tzosc.gcp.mongodb.net:27017 -
-destinationUsername atlasAdminUser --
destinationPassword atlasAdminPass --
httpStatusPort 8989 -j 10 2>&1 | tee
mongomirror.log
curl -X GET http://localhost:8989 |
python -m json.tool
Persist oplog token❗
Manual cleanup or use --drop❗

18. Extra Resources
https://www.mongodb.com/cloud/atlas/migrate

19. Post Steps

20. Post Steps
Monitor the deployment
Re-size oplog or instance size accordingly (72 hours recommended)❗
Update IP Whitelisting, if applicable
Set up backups, alerts, and other security settings

21. Key Takeaways
Do most of the "post work" upfront
Identify most suitable migration route
Have a generous maintenance window
Engage with Professional Services
> https://www.mongodb.com/contact/consulting/mongodb-atlas-foundation-migration-planning
Measure Twice, Cut Once!

22. Queries & Answers
diana@mongodb.com

23. Thank You!