MegaCLI - Mix of configured and unconfigured drives are not possible

When creating a RAID array using MegaCli, you may sometimes come across the below issue, which generally means that a Foreign Configuration may have existed on the drive:

 Mix of configured and unconfigured drives are not possible. 

To resolve this, you will first need to clear the drive, so that "Foreign State", is empty;

root@server [/opt/MegaRAID/MegaCli]# ./MegaCli64 -CfgForeign -Clear -A0

Foreign configuration 0 is cleared on controller 0.

Exit Code: 0x00

root@server [/opt/MegaRAID/MegaCli]# ./MegaCli64 -Pdlist -A0 | grep 'Foreign State'

Foreign State: None

Foreign State: None

Foreign State: None

Foreign State: None

Foreign State: None

Foreign State: None

Foreign State: None

Foreign State: None

Once that has been done, you should be able to add the drives within the RAID, as you normally would.

root@server [/opt/MegaRAID/MegaCli]# ./MegaCli64 -CfgLdAdd -r 1 [252:6, 252:7] -a0

Adapter 0: Created VD 2

Adapter 0: Configured the Adapter!!

Exit Code: 0x00