Enabling and working with premigration assessments for a task - Amazon Database Migration Service
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Enabling and working with premigration assessments for a task

A premigration assessment evaluates specified components of a database migration task to help identify any problems that might prevent a migration task from running as expected. This assessment gives you a chance to identify and fix issues before you run a new or modified task. This allows you to avoid delays related to task failures caused by missing requirements or known limitations.

Amazon DMS provides access to two different options for premigration assessments:

  • Data type assessment: A legacy report that provides a limited scope of assessments.

  • Premigration assessment run: Contains various types of individual assessments, including data type assessment results.


If you choose a premigration assessment run, you don't need to choose a data type assessment separately.

These options are described in the following topics:

  • Specifying, starting, and viewing premigration assessment runs: A premigration (recommended) assessment run specifies one or more individual assessments to run based on a new or existing migration task configuration. Each individual assessment evaluates a specific element of a supported source and/or target database from the perspective of criteria such as the migration type, supported objects, index configuration, and other task settings, such as table mappings that identify the schemas and tables to migrate.

    For example, an individual assessment might evaluate what source data types or primary key formats can or can't be migrated, possibly based on the Amazon DMS engine version. You can start and view the results of the latest assessment run and view the results of all prior assessment runs for a task either using the Amazon DMS Management Console or using the Amazon CLI and SDKs to access the Amazon DMS API. You can also view the results of prior assessment runs for a task in an Amazon S3 bucket that you have selected for Amazon DMS to store these results.


    The number and types of available individual assessments can increase over time. For more information about periodic updates, see Specifying individual assessments.

  • Starting and viewing data type assessments (Legacy): A data type (legacy) assessment returns the results of a single type of premigration assessment in a single JSON structure: the data types that might not be migrated correctly in a supported relational source database instance. This report returns the results for all problematic data types found in every schema and table in the source database that is selected for migration.