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Data Migration Service

DMS 1.0 Migration Guide

Data consistency validation

DMS ensures data consistency by verifying the data of objects. This article describes DMS data verification methods and how to view verification results.

Data verification methods

DMS supports CRC64 verification and sampling verification. Different scenarios require different data verification methods. Details are as follows:

Scenario	Validation method used	Enable method	Description
When retrieving data from the source, the source returns a CRC64 value.	CRC64 validation	No configuration is required in TOS; CRC64 validation is enabled by default.	After uploading an object to TOS, TOS calculates the CRC64 for the uploaded object, generates a CRC64 value, and returns it to DMS. DMS verifies the CRC64 value returned by the source and the CRC64 value returned by TOS to ensure data consistency between the source and destination.
When retrieving source data, the source does not return a CRC64 value, and sampling verification is not enabled for DMS.	CRC64 validation	No configuration is required in TOS. CRC64 validation is enabled by default.	After DMS obtains an object, it calculates the object's CRC64 value. Once the object is uploaded to TOS, TOS also generates a CRC64 value for the object and returns it to DMS. DMS validates the CRC64 value generated by DMS against the CRC64 value returned by TOS to ensure the consistency of data between DMS and the destination.
The source does not return the CRC64 value, but sampling verification is enabled in DMS.	Sampling verification tip If the source returns a CRC64 value and DMS enables the sampling verification feature, DMS will prioritize CRC64 verification.	You need to enable sampling verification when creating a migration task. For details, see Create Migration Task - Using Public Network.	DMS retrieves 100 bytes from each object on the source side and 100 corresponding bytes from the destination side, then validates them to ensure data consistency between the source and the destination.

Data verification results

The explanation for verification results using different methods is as follows:

CRC64 verification

If CRC64 verification fails, state in the migration list shows failed, and message displays crc_verify_failed. If CRC64 verification succeeds, state shows success.

Sampling verification

If sampling verification fails, state in the migration list shows failed, and message displays range check failed. If sampling verification succeeds, state shows success.

For more information about the migration list, see View migration list.

Last updated: 2026.02.02 11:05:22