Sorry but newbie here.
I have a 6 TB RAID configured device about a year old.
All has been set up ok but recently I had “Low Temperature " warning every few seconds (it lied, everything was warm!)
Rebooted and one RAID volume rebuilt - albeit slowly!
Today I have the same Low Temperature” Notification again and also:
" Volume Degraded
Volume 1 degraded. Please check status of drive by running Disk Test in Settings >> Utilities.
Thursday, 2018 November 22, 8:28:46 "
So, what now please