Which of the Following Feature Is Correct About the OceanStor

Which of the following feature is correct about the OceanStor V3 volume mirroring? (Multiple choice.)

A) After creating a mirrored volume for a normal LUN, the server read-write IO results in a change as a result of internal information exchange.
B) The amount of data actually stored on a LUN is 2G, the total copy of the data is 4G. A volume image is created for the LUN, the LUN is mirrored when the copy is generated during system creation.
C) You can configure a volume mirror for external LUNs or configure external LUNs as mirror copies.
D) When configuring volume mirroring, mirror copies are required from different disk domains.