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Because few enterprises perform public cloud deployments from scratch, chances are high they have Oracle Database...
running on premises. And moving those on-premises databases to cloud has its benefits. But an Oracle Database migration to AWS depends on a variety of factors.
Before undergoing an Oracle Database migration, IT teams must consider the size of the database, available network bandwidth between the local data center and AWS and which software edition is running in the data center. Business needs, such as the amount of time available to perform the move, are also important factors.
An Oracle Database migration could be accomplished in one step, but this requires a complete shutdown of the local database in order to extract and migrate the data to the new database in AWS. The process can take anywhere from one to three days, so this can be the most obtrusive migration strategy. Single-step database migrations are generally preferred for small businesses with limited database sizes that can tolerate prolonged database downtime during the migration.
Two-step migration strategies are common. The first step produces a point-in-time copy of the existing database, which can be moved to AWS without imposing any downtime on the local database. The local database continues to run during this process, so the actual migration can take as long as necessary -- there is almost no tangible disruption.
After the initial Oracle Database migration, a second step will capture, migrate and synchronize any incremental changes to the database. Once completed, the local Oracle Database will need to be shut down while the final changes are captured and migrated. This incremental step is considerably less involved than the initial synchronization, so the downtime is shorter. Once the final synchronization is complete, the AWS deployment takes over and the local database is decommissioned.
A third option promises zero downtime. This typically starts with an initial synchronization and then invokes a form of continuous data replication (CDR) to perform complete synchronization of the local and AWS database versions. A variety of tools, including Oracle's GoldenGate or third-party tools like Dbvisit Replicate and Attunity Replicate, can handle CDR. A business can make the switch to AWS once replication has synchronized the local and AWS databases. The CDR tool will continue to keep the instances synchronized. This option is typically reserved for the largest or most active Oracle database users who cannot tolerate any downtime. However, there is an added cost to use CDR, and continuous replication can potentially affect database or network performance.
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