i have faced the following erorr while performing data migration from SDEBINARY to BLOB using  the Geo-processing Tool (Migrate Storage (Data Management):

ERROR 000955: Error encountered migrating the database storage
Insufficient permissions[Feature Class Name]
Failed to execute(MigrateStorage)

as shown also in the below image:

This migration took place in version ArcGIS 10.1 SP1 in Oracle RDBMS environment.

so if you are in a version(release) below 10.1 that refer to this link:

http://support.esri.com/en/bugs/nimbus/TklNMDgwMDEw

 

The Solution i found is: to grant the schema user the following privileges:

GRANT ALTER ANY INDEX TO USER;
GRANT CREATE ANY INDEX TO USER;
GRANT CREATE TABLE TO USER;
GRANT DROP ANY INDEX TO USER;

Unfortunately this is not stated in any ESRI documentation (so far ….)

References for Data Migration:

http://resources.arcgis.com/en/help/main/10.1/index.html#//002n00000076000000

http://resources.arcgis.com/en/help/main/10.1/index.html#//00170000000q000000

http://resources.arcgis.com/en/help/main/10.2/index.html#//002n00000076000000

 

Also, the below is the data migration for each DBMS type in ArcGIS: