One of the most challenging aspects of cloud migration is moving your data. During the migration, where your data is stored can have a big effect on how fast your application runs. If you don’t migrate the data at the same time you migrate the services using the data, you risk needing to access your data over a distance between your on-premise and your cloud data centers, which can certainly cause latency and throughput issues.
Furthermore, maintaining data integrity, synchronization, and self-consistency throughout the transfer requires either stringent correlation or, worse, application downtime. The former may provide technical difficulties for the migrating teams, while the latter might not be acceptable for the company as a whole.
To keep your applications running well, you need to move both your data and the applications that use it at the same time. However, choosing how and when to move your data in relation to your services is a difficult decision. Companies often rely on the skills of a migration architect, whose job can make a big difference in how well a cloud migration goes.
Strategies to Minimize Downtime During a Cloud Data Migration
Whether you have an on-staff cloud architect or not, there are three primary strategies for migrating application data to the cloud:
- Offline copy migration
- Master/read replica switch migration
- Master/master migration
No matter if you’re moving a SQL database, a NoSQL database, or just raw data files, each method requires a different amount of work, affects the availability of your application differently, and puts your business at a different level of risk. You might few similarities between the different strategies discussed below, but the differences are in the details.
Strategy 1: Offline Copy Migration
The easiest way to move files is to make a copy offline. Bring down your on-premise application, copy the data from your on-premise database to the new cloud database, and then bring your on-premise application back online in the cloud.
An offline copy migration is simple, easy, and safe, but you’ll have to take your application offline to run it. If your dataset is very big, your application may be down for a long time. This will affect your customers and business, for sure.
Most applications can’t handle the amount of downtime that is needed for an offline copy migration. But you should think about this method if your business can handle some downtime and your dataset is small enough. It is the simplest, cheapest, and safest way to move your data to the cloud.
Strategy 2: Master/Read Replica Switch Migration
Reducing application downtime without considerably increasing the complexity of the data transfer is the primary aim of a master/read replica switch migration.
For this kind of migration, you start with your master version of your database running in your on-premise data center. Then, you set up a read-only copy of your database in the cloud with one-way data synchronization from your master database on-premise to your read-only database. At this point, you still make all updates and changes to the on-premise master, and the master syncs those changes with the cloud-based read replica. In most database systems, the master-replica model is used.
Even after you’ve moved your application to the cloud and made it work there, you’ll still write data to the on-premise master. At a certain time, you’ll “switch over” and switch the roles of master and read replica. The database in the cloud becomes the master, and the database on-site becomes a read-only copy. All write access to your on-premise database is moved at the same time to your cloud database.
During the switchover, you’ll need a short amount of downtime, but it’s a lot less than what you’d need with the offline copy method. But downtime is still downtime, so you should figure out what your business can handle.
Strategy 3: Master/Master Migration
When compared to the other two, this data migration strategy has the greatest potential for risk. But, if this strategy is implemented perfectly, then you can accomplish a smooth data migration process without any application downtime.
By setting up bi-directional synchronization between the two masters, you may synchronize all data from your on-premise database to the cloud and from the cloud to your on-premise database. This approach involves creating a replica of your on-premise database master in the cloud. You’re basically left with a normal multi-master database setup.
Once both databases have been set up, you may read and write data from anyone while maintaining synchronization between the two. You may do this freely, according to your timetable, and relocate your apps and services without having to worry about your data.
In fact, you can run instances of your application both on-premise and in the cloud to keep track of your migration better. You can also move your application’s traffic to the cloud without any downtime. If something goes wrong, you can roll back the migration and send traffic to the on-premise version of your database while you figure out what’s wrong.
At the end of your migration, just turn off your on-premise master and use your cloud master as your database. It is important to remember, though, that this method is not easy. Setting up a multi-master database is not easy, and there is a chance that the data will be wrong or that other bad things will happen. For example, what happens if you try to change the same information in both masters at the same time? Or, what happens if you try to read data from one master before the other master has been updated and the data has been synchronized?
So, this model only works if your application’s data access patterns and data management strategies can support it. You’ll also need application-specific synchronization and sync resolution routines to deal with sync problems as they come up.
Consider yourself lucky if this migration approach is compatible with your application, data, and company. In comparison to the other two methods, this one is the simplest and cleanest.
You can select any of the above-mentioned strategies for your cloud data migration. Select the strategy that fits your business and application data. AppleTech, can help you out with your data migration process. With a team of experienced data migration experts, AppleTech can make your cloud data migration process easier.
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