How to multiboot linux distros from different drive on Itanium based server

hello all,
I'm facing problem to bootup OS installed on different drives on my rx2660 HP integrity server.
System F/w :3.01 {4739]
BMC version:5.21
MP version :F.02.17

I have 3 hard drives on my server. I created Raid 0 on all the drives as below:-
LD #1 Raid 0 146GB (dev/cciss/c0d0)
LD #2 Raid 0 73GB (dev/cciss/c0d1)
LD #3 Raid 0 73GB (dev/cciss/c0d2)
I installed Rhat5.1 on LD1(c0d0).After finish installation, i could see the RHat5.1 boot entry on the EFI boot manager and I could boot up. Then I installed RH4(c0d1) and Suse10(c0d2) on my other 2 drives. Installation was completed successsfully but when it reboot after installation complete, I can't boot up to the OS installed on other drives although the boot entry of Rhat4 and Suse 10 appears at EFI boot manager.When i select the entry(Rhat 4 or Suse 10) it says file not found.
When I boot up to Rhat5.1, installed on the 1st drive and mount c0d1 to /mnt/floppy, i could see the files that has been installed on other drives.

Then I tried installing RH4 on the same drive on different partition on LD1 (C0d0) and i can successfully multiboot.I could also install Suse10 and boot if I install on the 1st drive different partition.
I'm not sure why I cannot setup multiboot when I install the OS on separate drives. Is there anything I need to do for the EFI boot manager to detect my other drives?

Even at EFI shell, when I switched to fs3: I only can find the files installed on the 1st drive.
I need to setup multiboot from OS installed from different drives but I only can do multiboot from 1 drive now..
Any help on this is much appreciated.
How the EFI boot manager load the OS?