I manage to get it boot after carbon copy the Mac OS. But the thing is that Areca mention its native support boot up via Raid Controller but seems not they should have it manage to detect the array while booting up the Mac so that fresh install can be perform.
If you read it again, you'll notice you have to get into the the system's firmware (motherboard settings), and select the boot location there (the array will show up).
But as you cannot do this on a Mac Pro, it's not possible. This isn't a fault of the card, but a restriction imposed by Apple. They do not allow users direct or indirect acces (via a utility) to those settings. There's some limited access, such as changes made by Disk Utility, and when you set the array as the boot location within OS X.
But to do a clean install directly to the array, you have to get access to the system settings (this is how you're normally able to put an OS installation in a system that doesn't have one). There's other reasons too, such as corruption (virus, bad sectors, ...) or the array failed, it's been fixed, and it's time to re-install the OS.
Clones are handy anyway, but in the case of the MP, it's an absolute necessity to transfer the OS to the array. No way around this.
So one more question nanofrog since you are the guru around here do you have any experience that while bootcamp there is no fan control in Windows environment which cause the Mac overheat while doing heavy Cpu load application.
It comes down to low level system interaction again (EFI has a portion called BIOS Emulation, which is what allows Windows and Linux to operate on the MP's board). Unfortunately, low level information doesn't pass properly between EFI and BIOS based hardware, even with this emulation active (disks are BIOS based, unless Apple's written EFI firmware or had it done; I think this is the case with the OEM DVD burners that shipped in 2009 systems to current - search the random seek/clicking thread/s here in MR). But the OEM ODD is an exception, as any HDD, SSD, or non Apple optical disk is BIOS based.
You see such things with fan control and low level formatting/scanning a disk (i.e. try to scan/remap a disk with/for bad sectors - you have to use a PC).
I've been google around but seems there no solution at all if so why do botcamp exist?
I'm not quite sure what you're asking here.
But I'll take a stab at it anyway...
Boot Camp was created so OS X and Windows could share a single disk, and is all Apple was interested in as to attract users interested in switching over from Windows (would allow them to load Windows and use their existing software until they became familiar with OS X and purchase software that can do the job natively in OS X.
As per the RAID card issues, it's to do with the firmware and how it interacts between the system and card. The RAID card controlls its own SAS or SATA controller/s, not the system. So without direct control, the system cannot make the changes to the disks to get BC to work (EFI uses GPT, BIOS uses MBR, though there are GPT implementations, which is how software based RAID works). Unfortunately, Windows's implementation and OS X's are not the same (seems the offsets are different, which is why a Windows based software RAID won't work on an MP either). Even what the RAID card do is partly proprietary due to a lack of complete/unified open standard.
There's one company that made it (CalDigit) work by using a cable that connected the card to the system's SATA ports (ICH). Essentially a bypass/hack method that allowed the array to be shared (means of giving the system direct access). It's out of production as I understand it, and it was slow (junk too when it first released <very unstable>, and the support dept. was a disaster).
