Hi I just wanna disable the default RAID in my server IBM System X3400 M2 Server(7837-24X),i have 3 disk drives SAS. I want to make them a JBOD "Just a Bunch Of Disks", because I want to install in the drive 0 CentOS, and the other two make them cache files for a squid server. I disable the RAID in the BIOS:

System Settings/Adapters and UEFI drivers/LSI Logic Fusion MPT SAS Driver
-PciRoot(0x0)/Pci(0x3,0X0)/Pci(0x0,0x0)

LSI Logic MPT Setup Utility

RAID Properties/Delete Array

Later I boot the CentOS live CD and install the OS in the drive 0, and the others 2 mounted like this:

*LVM Volume Groups
vg_proxyserver     139508
lv_root            51200    /    ext4
lv_home        84276    /home    ext4
lv_swap        4032
Hard Drive
sdb(/dev/sdb)
free        140011
sdc(/dev/sdc)
free        140011
sdd(/dev/sdd)
sdd1        500    /boot    ext4
sdd2        139512 vg_proxyserver    physical volume(LVM)

But when I restart the server give me the error:

Boot failed Hard Disk 0
UEFI PXE PciRoot(0x0)/Pci(0x1,0X0)/Pci(0x0,0x0)/MAC(001A64B15130,0X0))
........PXE-E18:Server response timeout.
UEFI PXE PciRoot(0x0)/Pci(0x1,0X0)/Pci(0x0,0x0)/MAC(001A64B15132,0X0))
........PXE-E18:Server response timeout.

and the OS not start. The IBM force me to do a RAID?,why?