Deploying the migrated and tested Oracle database within a business environment can be difficult. Therefore, you may need to consider different rollout strategies depending on your environment. Several rollout strategies are identified for you, but you may use another approach if that is recommended by your organization.
During the deployment phase, you move the destination database from a development to a production environment. A group separate from the migration and testing team, may perform the deployment phase, such as the in-house IT department.
Deployment involves the following:
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Migrating Third-Party Databases
The strategy that you use for migrating a third-party database to an Oracle database must take into consideration the users and the type of business that may be affected during the transition period. For example, you may use the Big Bang approach because you do not have enough systems to run the source database and Oracle database simultaneously. Otherwise, you may want to use the Phased approach to make sure that the system is operating in the user environment correctly before it is released to the general user population. You can use one of the following approaches.
Using the Phased approach, you migrate groups of users at different times. You may decide to migrate a department or a subset of the complete user-base. The users that you select should represent a cross-section of the complete user-base. This approach allows you to profile users as you introduce them to the Oracle database. You can reconfigure the system so that only selected users are affected by the migration and unscheduled outages only affect a small percentage of the user population. This approach may affect the work of the users you migrated. However, because the number of users is limited, support services are not overloaded with issues.
The Phased approach allows you to debug scalability issues as the number of migrated users increases. However, using this approach may mean that you must migrate data to and from legacy systems during the migration process. The application architecture must support a phased approach.
Using the Big Bang approach, you migrate all of the users at the same time. This approach may cause schedule outages during the time you are removing the old system, migrating the data, deploying the Oracle system, and testing that the system is operating correctly. This approach relies on you testing the database on the same scale as the original database. It has the advantage of minimal data conversion and synchronization with the original database because that database is switched off. The disadvantage is that this approach can be labor intensive and disruptive to business activities due to the switch over period needed to install the Oracle database and perform the other migration project tasks.
Using the Parallel approach, you maintain both the source database and destination Oracle database simultaneously. To ensure that the application behaves the same way in the production environment for the source database and destination database, you enter data in both databases and analyze the data results. The advantage of this approach is if problems occur in the destination database, users can continue using the source database. The disadvantage of the Parallel approach is that running and maintaining both the source and the destination database may require more resources and hardware than other approaches.
There are several ways to deploy the destination database. The following task is an example that you should use as a guideline for deploying the destination database.
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Note: If you have a complex scenario as defined in Table: Complex and Simple Scenarios, Oracle recommends that you complete all of the deployment tasks. However, if you have a simple scenario, you should choose the deployment tasks appropriate to your organization. |
Configure the hardware, if necessary.
In a large scale or complex environment, you must design the disk layout to correspond with the database design. If you use redundant disks, align them in stripes that you can increase as the destination database evolves. You must install and configure the necessary disks, check the memory, and configure the system.
Make sure the operating system meets the parameters of the Oracle configuration.
Before installing any Oracle software, make sure that you have modified all system parameters. For more information about modifying system parameters, see the relevant installation guide for your platform, such as Solaris Operating System.
Install the Oracle software.
Aside from the Oracle software that allows you to create an Oracle database, you may need to install ancillary software to support the application, such as Extract Transformation and Load (ETL) Software for data warehousing.
Create the destination database from the source database and migrate the data to the Oracle database.
There are several ways of putting the destination database into production after testing it, such as:
Place the successfully tested database into production. The test system is now the production system.
Use Oracle Export to extract the destination database from the successfully tested database and use Oracle Import to create that database within the production environment.
Use the tested migration scripts to create the Oracle database and populate it with data using SQL*Loader.
Perform the final checks on the destination database and applications.
Place the destination database into production using one of the rollout strategies.
Perform a final audit by doing the following:
Audit the integrity of the data
Audit the validity of the processes, such as back-up and recovery
Obtain sign-off for the project, if necessary