The megaraid driver fails to detect the array during the OS installation. While loading, the driver displays the following message on one of the text console:
megaraid mailbox: wait for FW to boot [counter]
Omega 8220-SR, 8240-SR, 8320-SR
This symptom only occurs on servers configured with 16GB of memory or higher. As a workaround, enter 'linux mem=2000M' to start the Red Hat installation.