My Book Studio Edition RAID 1 Mirroring

I have a My Book Studio Edition 2 that I have formatted for RAID 1 Mirroring. How can I be sure the mirroring is working? I know that I can see the status of each drives in WD Raid manager but I d like to be sure that my files are copied in both drives. Is there a way to access the files in the 2nd drive to check this out? Also if the first disk fails, how can I access to the 2nd one? Should I unscrew the box and replace the failed disk by the 2nd one? Thanks.

I think the only way is to connect disk 2 to a Linux computer, but directly from the my book case only disk 1 is accessible in RAID 1. In case disk 1 fails, replace it and the my book will rebuild the RAID.