My sys admin arrived to find the box in a bsod or locked up state. Upon reboot we got the foreign config error. The box was an aged Dell Poweredge 2950 with a Dell Perc 6i RAID controller was reporting a foreign configuration present on the adapter.
Now we know this was a raid0 array using 3 disks. I know, I know, this is a horrible configuration that was inherited and should never be used if the data is important.
I knew the three disks present were the original 3 disks in the array. Using the raid configuration console accessible at boot using Ctrl-R I was able to inspect the configuration on the disk and controller.
The adapter reported a 2 disk configuration while the foreign reported 3 disks.
We choose to import the foreign configuration present on disk two of a disk 1,2,3 array.
Smooth as butter!