RAID-1 mirroring is about redundancy— failure of one drive is a non-event in terms of functionality (though you will want to replace the failed drive). The resilience of mirroring comes from the fact that all drives in a mirror are identical copies, so that when a drive fails (all do eventually), the remaining drive is still operational and intact. The GMax has two drives internally, so one of the two can fail while retaining full access to your data.
The beauty of the GMax is that both the user (you) and the Mac see it as one drive. There is no special configuration, no special driver— just plug and play, knowing that your data is protected in the event of a drive failure. If a hard drive failure occurs, once the new drive is installed, the Guardian MAXimus will automatically rebuild the Mirror without loss of data to time using the remaining intact drive.