We have dual controllers on FAS2040. Each controller has 1 aggregate. SAS disk on one, SATA on the other. Both configured with RAID-DP. We have 1 spare disk assigned to each controller. Had a failed disk and now the System Manager has a notification "There are insufficient spare disks". With RAID-DP and this lost spare, what happens if we lose another disk waiting for the replacement to arrive? Should EACH controller have 2 spares?