I installed CentOS 7 on my HP ProLiant Microserver Gen8 on a SSD. I'm using the internal SD card slot as boot device while all other partitions are located on my SSD to circumvent the limitations of the storage controller. After days of OS configuration and software installation I realized that I forgot to install the RAID driver. Regarding to the installation instructions the driver must be installed on the OS installation. This seems reasonable to me if I want to install the OS on a RAID array. But is it obligatory? How can I install it without re-installing my system?