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Here's the situation: A Windows RAID 1 has partially failed. The broken disk was replaced with a new disk. The old two disks do not have Advanced Format (bigger sector size). The new replacement disk does have it. Windows refuses to add the new disk into the existing RAID because of the differing sector size. The goal is to restore the RAID 1.

My plan so far was to use a cloning software to clone the entire OS disk over to the replacement disk. Then, simply boot off of the replacement disk. I have a KVM interface hooked up to the server so that I can operate the BIOS and the boot menu.

The cloning worked and I can use the BIOS boot menu to boot from the new disk. But the Windows boot loader has the same cloned BCD database and redirects the boot to the old disk! I assume that it finds the old disk by its NT signature. So the booting starts from the special 100MB Windows boot partition on the replacement disk and uses the /Windows files on the old disk.

How can I make the two disks independent so that I can use the boot menu to choose what disk to boot off of?

While experimenting with bootrec /rebuildbcd I even got into a weird state where I did boot from the replacement disk but with drive letter D. Now about everything will be broken when the OS driver letter changes so I quickly ended that experiment.

It looks like I would need to install a new BCD on the replacement disk and also new drive letters. I'm unsure how to do that and whether that is enough to get this working.

I'm unwilling to risk the bootability of the old disk until the new one is guaranteed to work. I'm working with limited resources here. I'd very much like to avoid involving expensive data center technicians.

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    Just put the new disk into the machine, boot from your windows disk, go to recovery console and /reuildbcd. That will put the new disks signature in to BCD. Then reboot the machine, but the old disk there and copy the BCD parameters from the boot.ini into the new one (as it will offer a 2nd boot option).
    – bjoster
    Apr 28, 2016 at 14:00
  • It might also help to first prepare the new disk by completely wiping out any partitions there first, maybe on another computer. I use AOMEI software for that on my Windows 7 machine to prep disks that need to be blanked (not wiped, although it can do that, too, but it takes forever and doesn't gain you anything in your scenario). Alternatively, again on another PC, load up a LiveCD and use gparted to clear it of any partitions. Then, as @bjoster said, the system will know what to do with it when you add it to the RAID set.
    – SDsolar
    Jul 14, 2017 at 23:56
  • If you haven't already, make sure you have a copy of the original RAID 1 disk on hand. I find the best way to do that is to put in a second drive, and DON'T add it to the RAID set in BIOS, boot with a LiveCD (and install disk will usually work), then use sudo fdisk -l to see which is which, then dd if=/dev/sdx of=/dev/sdy to make an exact duplicate. That way no matter what happens with RAID you still retain all the data. RAID in BIOS can really create problems unless you start with a fresh no-partition disk and it would be a shame to lost your data due to lack of preparation.
    – SDsolar
    Jul 15, 2017 at 0:02

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