Sometimes, you don't migrate because you want to, you migrate because you have to. Legacy systems can eventually reach a point where they can no longer keep up with the demands of a modern business, and maintaining them might become a risk rather than an asset.

Here are some key reasons you might need a database migration:

• End-of-life hardware: Your physical servers are aging, and the manufacturer no longer supports the hardware or the operating system
• Performance bottlenecks: Your current database architecture can’t handle your data volume or traffic spikes, causing slow experiences for your users
• Security and compliance: Legacy systems may lack the modern security features, patches, or auditing capabilities required to meet today’s regulatory standards
• Vendor lock-in: You’re tied to a proprietary, expensive, or inflexible license that limits your ability to innovate or choose the best tools for your specific needs
• Data silos: Your data is trapped in isolated, on-premises systems, making it difficult to feed into modern analytics or AI models that your team needs to stay competitive

When your existing architecture can no longer support your operational requirements, migration is the necessary next step to keep your business running securely and efficiently.

When you move your database, you’ll likely hear the terms homogeneous and heterogeneous. Understanding the difference helps you plan how much work your technical team needs to do.

There are four common strategies for migrating data. Visit cloud migration strategies for a deep dive and recommended strategies.

• Rehost: lift and shift. The simplest way to migrate your data, this makes a complete copy of your existing database into another environment, usually together with the rest of the application stack. [homogeneous]
• Replatform: lift and optimize. This strategy copies the databases, applications and virtual machines and then optimizes them for the new cloud environment. This can be a heterogeneous migration, such as when moving from a commercial database to a PostgreSQL-compatible database such as AlloyDB. [homogeneous/heterogeneous]
• Refactor: move and improve. A refactoring cloud migration strategy involves re-engineering applications to align with cloud-native principles, requiring changes to the application code itself. [usually heterogeneous]
• Rebuild. A rebuilding cloud migration strategy rewrites an architecture and application entirely for the cloud. Depending on your application, this can be cheaper than refactoring. [usually heterogeneous]

While you can migrate your database between virtually any two locations, the majority of migrations are either from on-premises to cloud or from one cloud to another.

There are many reasons why companies are migrating to the cloud (or to an alternate cloud provider):

• Faster application development
• Improved performance and scalability 
• Cost savings
• Security
• A wider range of features, in particular AI-related ones
• A shift from an on-premises capital expenditure (CapEx), common with traditional licensed databases, to operating expenditure (OpEx), common with cloud service

Learn more about the benefits of migrating to the cloud.

Many organizations are moving their on-premises workloads to the cloud for the reasons discussed above. Migrations from on-premises require additional considerations compared to cloud-to-cloud migrations.

A common strategy to migrate on-premises workloads is rehosting, which copies your entire workload over to the cloud. Doing this reaps the security, reliability, and some cost benefits associated with cloud migration. 

Something to note, however, is that this strategy can also transfer any existing inefficiencies from the on-premises architecture over to the cloud infrastructure, which can cause you to miss out on the larger cost savings and efficiencies associated with a cloud-native architecture. You may also miss the rich functionality of the cloud in areas like disaster recovery, analytics integration, AI/ML services, and a marketplace of partner offerings.

Make sure to maintain the security of your data during the migration, particularly between different types of environments. One way to ensure the best security is to use a trusted database migration service.

Data and database migrations can be complex. It is essential to ensure that your enterprise’s data, as well as its organization and functions, move to the new architecture seamlessly. If done improperly, you may experience data loss, workloads not running properly, or security issues.

Some best practices:

• Understand your data. It’s essential to know what your needs are for your specific business case and application.
• Evaluate where your business is heading. Taking scaling into consideration is key to choosing the right architecture and provider. 
• Test with feature flags. Use feature flags to roll out your new database to a small group of users first. This lets you test the system safely before a full launch.
• Select the right data migration strategy that makes sense for your situation.
• Follow a data migration plan carefully to ensure optimum performance.

For an in-depth look into the process, read concepts and principles of data migration and setting up and executing the data migration process.

Although the details will vary based on your specific business case, these are the basic steps of a successful migration:

1. Identify where all of your data currently is, what format it’s in, and where it should be post-migration. You may determine you don’t need to migrate all of it, and can archive or delete old data. This also is a key time to note any potential risks of migration.
2. Plan your migration strategy. Determine which migration strategy will work best, decide whether downtime can happen during business hours, and set a budget. 
3. Execute your migration. You may want to use a migration service for implementation.
4. Test your new system before the cutover. This enables you to identify any workloads that aren’t working appropriately and resolve any issues. You may need to run both databases concurrently, requiring replication of data from one system to the other. Only once you have confirmed all workloads are operating on the new database as expected can you shut down your old system.

The number of phases your migration will take depends on your organization’s existing setup and timeline. For example, migrating from a self-managed, on-premises deployment to a managed cloud service can be accomplished in a single step. Or, if there is time pressure, you can first migrate to a self-managed database in the cloud, and then switch to a fully managed solution.

Ideally, database migration isn’t a process your company will do often. To make the most of your migration, here are a few key questions to think about: