Planning the Migration v2.6
Review this section for items EDB recommends you include in your migration plan.
Testing and Verification
Every organization will have different policies and capabilities which define what should be done in which environment. Some organizations restore a production database after migration to a temporary system in the test environment, where others rather test the process in a test environment, and expect their production environment to behave the same as their test environment. Whatever best suits your organization, make sure all of the following are updated and verified:
Deployment and management automation
Processes for restoring a database
Integrations such as integrations with the backup infrastructure
EDB advises to set up a temporary test system, specifically for onboarding the new tool, so that all of these actions can take place without impacting the existing environments. Make sure your test plan includes standing up the test system, planning for all actions that should take place on this test system, and cleaning up the system after migration.
Some organizations also require verifying a successful restore for every database that has been migrated to the new tool.
Sizing Considerations
Depending on the actual migration, different sizing considerations apply. Two distinct migration paths exist:
New storage will be attached for the new backups.
In this case, a good starting point would be to size the storage equally to the current sizing requirements. Note this might be a good opportunity to scale down oversized storage locations. Optionally, consider running both backup tools simultaneously. If the impact is acceptable, it can be an option for rollback and extra security for successful backups. EDB recommends this approach as it is the most straightforward and least error prone.
The mount point for the existing backups is reused for the backups.
An important note to make is that the repositories for the different tools have different layouts, and are not interchangeable. That means that the exact location needs to be distinct. But they can exist on the same mount point. The upside is that the extra required storage can be expected to be less than when attaching new storage. That being said, during migration extra storage is still required, and downscaling might not be an option. Furthermore, this option leaves no room to run both backup tools simultaneously. Extra sizing requirements would depend on your exact backup scheme, maintenance schema, and the size difference for differential backups. A good starting point would be to prepare for an extra set of backups (one full and all differentials), and an extra full backup. Make sure that the monitoring thresholds are also properly adjusted as required.
Note that it is crucial that you make sure that compression options are configured similarly between the old and new tool. Alternatively, extra storage space is required to compensate for the backup and/or WAL size.
During the planning phase the following needs to be taken care of:
Select the approach.
Size the expected extra storage and check for availability.
Plan to attach or increase the extra storage as part of the migration plan.
Next to the expected extra storage, also make sure that during the migration extra storage space is directly available should it be required due to unforeseen circumstances.
When using the first approach (extra mount point), plan to clean out the old storage after migration. Make sure that the old repositories are preserved long enough to meet your organization's rollback policies.
Resource Availability and Timeline Communication
Depending on the size of your environment, the number of available DBAs to run the migrations, and the amount of automation, the migration can take a considerable amount of time. During the migration your organization may be stressed with some parts of the environment already running with the new tool, extra storage requirements being identified, and DBA resources focused on the migration and less available for other tasks.
It is therefore crucial to plan the migration per environment and derive the duration of the migration from that plan. Communicate these timelines to the rest of the organization so that they are aware that the DBA team is extra occupied during this period of time. Furthermore, make sure that the storage team is available to prepare for and attach the extra storage as required.