Data Survey

The following describes the data survey.

**Table 1** Data survey
Survey Content	Purpose	Example
Data type	Select a proper migration tool based on the data type.	HDFS, HBase, and MySQL
Data volume	Obtain historical data volume to evaluate the historical data migration period. Obtain daily incremental data to evaluate the daily incremental data synchronization period.	Historical data: X PB Daily incremental data: Y TB
Data layers	Survey the data layers to determine the migration priority and data verification standards.	Data access layer, intermediate layer, and result layer
Data permissions	Determine the permission data migration method based on the source data permission control component.	Sentry and Ranger
Data importance	Survey data helps identify core data from non-core data, setting migration priorities and data verification standards.	Core data: transaction data Non-core data: log data
Data update frequency	Determine the data migration plan and verification plan based on the update frequency.	Daily/weekly/monthly/real-time update
Task execution interval	Stagger peak hours of data migration, data verification, and services.	Offline task execution before and after work