Replacing a failed disk in RAID on an OVHcloud dedicated server

Yesterday morning, I woke up to some Discord messages saying that one of my websites was offline. Not a great way to start off the morning! I tried to first ascertain the scope of the issue—turns out none of my services were accessible at all from that one dedicated server. Panic started to set in a bit… did I forget to pay my monthly server bill? Did the server get hacked? Or did the server burn down?