How to setup boot partition-->win 7 partition?


Extraordinary Member
In the early days of Win7 it was usual to install one Win7 system on a partition (say A) and let it be called during bootup from the partition independent MBR from the hard disk directly:

MBR ---> partititon "A" (with Win7)

Then it became more and more popular to install two different Win 7 systems (one work one for test/reserve) on two separate partitions (say A and B) and let the user choose at bootup in a BootManager menu which of the two should be started.
The BootManager can be put in a third, small partition (say BM with 100MB size). So the possible call chain is like:

MBR ---> partition "BM" (with BootManager) ---> partition "A" (with first Win7)
MBR ---> partition "BM" (with BootManager) ---> partition "B" (with second Win7)

Ok, I know how to install a Win 7 on a partition.

1.) But how do I tell which software: "Hey, put a Boot Manager on small partition BM and call this from MBR.
Then in BootManager link to all (=both) existing real, full Win 7 installations on partition A and B)"

2.) Can I do this from within one of the two running Win 7 systems or do I need another software for setup?

3.9 Do I have to install both Win 7 systems at FIRST before BootManager or can I install and add additional Win 7 systems later to BootManager menu?


As far as I know each OS has to have the MBR installed with it on same HDD/SSD, with out having the MBR on the HDD with the OS installed you'll end up with the error message "no OS found". The only way I know of to accomplish something similar is to have the different OS on different HDD's with it's own MBR and then use the boot manager menu at boot up to select what HDD to use which OS is installed on it.

This is the exact same setup I'm using...3 HDD's with different OS installed, each has it's own MBR. The key to doing this type of setup is; having the other HDD's unplugged when installing the 2nd, 3rd OS's. If not the MBR by default be put on the C drive and then the error message "no OS found" will pop up.

1. install HDD and then install OS 1
2. turn off pc, unplug HDD 1 and install HDD 2, boot up and install 2nd OS on HDD 2.
3. turn off pc, unplug HDD 2 and install HDD 3, boot up and install 3rd OS on HDD 3
4. at boot up if you don't use the boot manger to select the HDD to be use with it's OS installed by default the C drive will be used. Just make sure the OS you want to use as your primary OS is on the C drive.
5. to select the boot manager at boot up, hit the F12 key for the quick launch of the boot manager


Excellent Member
Microsoft Community Contributor
In actuality, in the early days of Windows 7, as it is today, a 100 MB System partition was created which contained the boot files. It became popular to install Windows 7 without that partition and just put the boot files directly in the OS partition.

If you have two licenses, I suppose you might want to put both installs on the same system. But all you have to do is install one version and when you install the second copy, it will use the current boot to add its own configuration.

The MBR basically just tells your system what type of boot configuration you are using, such as for XP or for Windows 7 and 8. But all the boot files are in the Active partition for a Legacy install. You can put the OS on a separate drive, if you want, but the boot files have to be in that one partition unless you install as a parallel configuration where you can boot to either drive independently.


Extraordinary Member


Assume I have currently a Win 7 system with the boot files on the same partition as the remaining windows 7 files.

Can I somehow separate the boot files and move them to the 100 MB "System partition" (of cause without re-installing Win7)?

The problem with a configuration like...

- Partition 1: Windows 7 installation "main" + boot files for Windows 7 installations "main" and "reserve"
- Partition 2: Windows 7 installation "reserve" without boot files that if the whole partition 1 crashes then users cannot start the Win 7 system on partition 2 neither.

I need a startable second Windows 7 installation independently from the "main" Windows 7 installation.



Excellent Member
Microsoft Community Contributor
The bcdboot.exe utility will place the boot files where you want. If you put a drive letter on the small partition, say t: and then use the command line below, it will but the boot files for current OS in that partition. To boot to that partition you would need to make it active. When you have it working, remove the drive letter from the small partition.

bcdboot C:\windows /s T:

Where C: is the drive letter of your Windows Install. If you do this from a booted media command prompt, it may not be c: so check to make sure you are using the correct drive letter

You will have to register the Recovery Tools location in the BCD store, or you will not be able to use the F9 options during boot.

To add the second OS, use the Bootrec /rebuildbcd command from the command prompt after booting to recovery or install media.

Note: This discussion is about MBR installs. A UEFI install will need other steps.

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