ESXi 6.0 showing storage as Normal, Degraded

Hi,

We need help on our newly setup ESXi server. It appears that the disk status is Normal, Degraded. Anybody who can help on how to change/set this to normal? Or what have we done wrong? We have also reported this to Dell since we are using PowerEdge R640 and they said that iDrac logs indicate that everything is optimal. Your help will be very much appreciated.