Why does RAID 0 massively increase boot time?

[Master Disaster]

If I boot from a single SSD I'm into windows in less than 5 seconds (on Win 8.1, full UEFI install with fast boot). When I RAID up both my drives it increases to over 12 seconds.

Can anyone shed some light on this. I didn't post this in trouble shooting cause its not really broken, I know this happens with RAID 0, I'm just hoping someone can explain why

[AlwaysFSX]

Raid controller slows it down I guess?

[ionbasa]

If I boot from a single SSD I'm into windows in less than 5 seconds (on Win 8.1, full UEFI install with fast boot). When I RAID up both my drives it increases to over 12 seconds.

Can anyone shed some light on this. I didn't post this in trouble shooting cause its not really broken, I know this happens with RAID 0, I'm just hoping someone can explain why

It has to due with the fact that the RAID controller has to initialize at a hardware level. This means the BIOS/UEFI has to load the RAID chipsets ROM module at boot. Once that is done, then the controller has to initialize the drive pool.

 

EDIT:

To elaborate. When you boot from RAID, the RAID controller has its own 'ROM" (called an Option ROM) that is loaded during the bootup process by your motherboard's BIOS/UEFI.

The UEFI bootup process looks like this:

When enabling RAID, you are adding at least two extra steps in the chain.

The first: loading the Option ROM during the DXE step. The second step happens within the first step, and that involves having the RAID controller check and initialize the drive pool.

 

NOTE: This is fairly simplified. Just know that you're adding more steps to the final boot process. 

[KemoKa]

This^

better than I could have put it myself. Basically your motherboard has to do more stuff in order to boot anyway. If you're going for straight-up speed, the best thing would be a Revodrive.