The Migrate Storage geoprocessing tool (ArcToolbox > Data Management Tools > Database > Migrate Storage), when run on a batch of feature classes stored in Oracle, can exceed the Oracle open_cursors default limit of 300. When this happens, the tool returns the following generic message:
"ERROR 000955: Error encountered migrating the database storage of <connection>
Failed to execute MigrateStorage."
In addition, the SDE error log contains a message stating that the open_cursors limit has been exceeded.
Oracle cursors are incorrectly left open during the conversion of each feature class. Converting 200 or more feature classes can open enough cursors to exceed Oracle's default open_cursor limit of 300.
When the tool finishes migrating a batch of feature classes, the cursors are freed.
To increase the open_cursor, connect to Oracle as the SYSTEM user and issue the following SQL statement:
ALTER SYSTEM SET OPEN_CURSORS=2000 SCOPE=BOTH;