Hi. The Raid-adapter is probably not on the HCL seems to be a what it commonly known as a "software-raid".
Unless someone have hacked a driver (unlikely) then your best bet is to turn off the RAID and use it as a normal SATA-controller instead.
That means that you will see 2 disks and not any Raid and they will not be protected from failures.
To get proper raid, get a hardware raid-card that is listed on the VMware HCL.
// Linjo