Supermicro SYS-5027R-WRF Flashing red LED on two HDD bays

We have a Supermicro SYS-5027R-WRF running FreeBSD 12 and using root on ZFS. The chassis has eight drive bays the lower four of which hold the drives assigned to the ZFS pool. The upper four bays contain hdds but are not configured into the OS and have not been partitioned.

The activity lights on the four configured drive flash green as expected. However two of the unconfigured bays have flashing red LED. The manual says that this indicates that the drives are 'rebuilding'.

Red: When this LED fl ashes it indicates the drive is rebuilding.

We are not using any builtin RAID and these bays have never been configured. What is being rebuilt and how do we turn it off? This issue has existed for some time but because these drives were treated as spares we never investigated the cause. Now we wish to create a second ZFS pool using these bays and need to discover what going on and how to correct it.

This is a running server and cannot be shutdown during normal work hours. We have IPMI working and we can connect by SOL using the JavaScript applet and by web console. I am curious to see if the RAID feature has some setting that might be causing this but that requires looking at the BIOS as far as I know and that requires rebooting the host to see the settings.

Is there anything we can do while the system is live to determine what is actually causing the drive LEDs to flash?