What happens with two bootable SATA drives active simultaneously?

[KingFatty]

Hi all,

If I have one bootable hard drive, and one bootable SSD, both SATA and both active, how does my computer know which to boot from? it's Windows 7 x64 pro that will be actively installed on both drives.

I'm going to disconnect my current hard drive that has Win 7 x64 pro, and leave it disconnected while I install a new SSD and Win 7 x64 pro using the same windows installation key.

After getting the SSD all set up, what happens when I reconnect the hard drive and reboot? Won't both hard drives try to boot the computer, how will it decide who gets precedence?

Ideally I don't want to mess with the hard drive and make it unbootable, because I plan to remove the SSD and boot from the hard drive later on.

Is this a matter of simply assigning boot priority in my BIOS (or perhaps swapping the SATA cables into various different SATA ports), or do I have to mess around with bootup stuff stored on the hard drive itself?

 

[groberts101]

simply choose the proper boot order you prefer.

ofetn times when the drive is disconnected/reconnected it's then necessary to go back into the bios and make sure your preference is still set correctly or the system may boot to the other drive.

What may be easier in the future is to build that image on one drive and then use it to copy to the other(or any used in the future for that matter so long as the hardware does not drastically change). Saves large amounts of time/tweaking in the long run.

 

[Diogenes2]

Some Motherboards have a function key you can press to select boot drive during POST ..
I think it's F8 on mine ..

 

[VirtualLarry]

The BIOS will only boot from whichever drive you select. Even if two drives have bootable MBRs and partitions. "Active" refers to the particular entry in the MBR partition table, which primary partition gets booted, once the BIOS starts to boot that HD.

 

[corkyg]

SATA drives are numbered. Thus, a specific one can be made the boot drive in BIOS.

 

[piasabird]

So does Microsoft have a bootloader?

 

[piasabird]

http://windows7forums.com/windows-7-support/2950-windows-7-boot-ini-file.html

Helps if one of the drives has a boot loader. Probably better to put it on the hard drive since it is more stable and dependable (Hopefully). I think windwos has a bootloader, but some third party products may work better. Such things can be problematic and prone to total loss of drive accessability.

 

[KingFatty]

I can now select the drive to boot from in BIOS. Interestingly, the selection is not under the boot priority, because that only lists the first boot drive. There is another setting, where you order the boot drives. So that's where I swap the position of the HDD and the SSD, whichever is listed first will boot from.

Also noticed something: when I boot from the HDD and open file explorer, I see the SSD as one drive and it's 100MB system reserved partition is hidden. But, when I boot from the SSD, I see the HDD main partition and the HDD 100MB hidden partition. I'd normally think this was due to revealing hidden files as a setting in that install of windows, but the SSD's hidden partition remains hidden. So I'm not sure why one hidden partition is visible and not the other, when I boot under the SSD.