My Book Mirror maximum disk size

WD External Drives External Drives for PC
2

Hello,

Not sure if you will be able to use bigger drives than the one that came with the unit due to the time that your unit was manufacturer. However, they are other users that reported that they were able to do so.

Check the link below 

http://community.wd.com/t5/Other-Network-Drives/MBWE-ii-increase-capacity-to-2x-2TB/m-p/426060#M8377