Book Image

MongoDB High Availability

By : Afshin Mehrabani
Book Image

MongoDB High Availability

By: Afshin Mehrabani

Overview of this book

Table of Contents (17 chapters)
MongoDB High Availability
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Understanding the migration process


As you already learned in previous chapters, there are two main ways to deploy a MongoDB instance: using replica sets for deployment in a production environment and using a single mongod instance for development or testing.

Although it's not a good idea to use a single mongod instance for the production environment, we will introduce both methods to move a single mongod instance and replica set.

First of all, there is a simple hack to migrate a replica set to another server. As you know, if you add a new member to an existing replica set, this member will synchronize its oplog with the current primary node. This is shown in the following diagram:

Let's assume we have a primary node in our existing server, then we add a new node to the existing replica set. Obviously, initially it will be a secondary node. This secondary node is empty, but it synchronizes its oplog with the primary server inside the existing server. This depends on the amount of data on the...