Creating a RAID array on OVH Servers with Hardware RAID (MegaRAID)
Type this into your terminal:
MegaCli -CfgLDAdd -R1[252:2,252:3] -a0
Where R1 means RAID-1. So R0 means RAID-0 etc.
252:2 and 252:3 are the disk numbers as they appear in MegaCLI. 2,3 were my two SATA disks. The SSD's were already configured as RAID-1 when installing the OS. Not sure what 252 means.