The boot manager is a particular program that is automatically loaded when the PC is turned on and that allows you to choose the operating system to boot if more than one is installed (dual boot or multi boot configuration).
The boot manager is responsible for selecting the kernel of the operating system the user wants to run. Windows Boot Manager is the boot manager that uses the Microsoft operating system while GRUB or LILO are used in Linux.
The boot manager is a small executable (called BOOTMGR) which is generally (except in special cases) located in the system partition created during the Windows installation.
Once the boot manager is loaded, in Windows “the ball” goes to the boot loader that continues with the boot process of the operating system chosen by the user from the boot menu.
BCD: What it Does and Why to Manage it With EasyBCD
Windows Boot Manager draws on the contents of the BCD (Boot Configuration Data) file to obtain information on which operating systems are installed on the machine, on which partition and where the corresponding boot loader is located.
As we explained in the article Installing multiple Windows operating systems on a PC, you can install multiple copies of Windows on the same machine by setting up a dual boot or multi boot configuration.
Taking care to install the new version of Windows on a different partition than the one containing the other copy of the operating system, the contents of the BCD file will be automatically updated.
EasyBCD is an excellent software, also available in a free version, that allows you to manage the Windows BCD file without having to try the complexity of the BCDEdit command integrated in Windows and based only on the command line.
Create a backup copy of the BCD file and repair it when something goes wrong.
When installing multiple operating systems, it may happen that the BCD file gets corrupted (see the article mentioned in the previous paragraph).
To avoid any problems, the advice is to start EasyBCD and click Backup/BCD repair.
At the Backup and Restore Settings pane of the Startup Manager, you will need to set the folder where you want to store the backup copy of the BCD file. Creating the backup is bootable by clicking Backup Settings.
Selecting the option Recreate and/or repair boot files then clicking on Do the action, EasyBCD will regenerate a damaged BCD file.
By clicking on Modify startup menu you can change (increase or decrease) the countdown, i.e. the time that elapses before the automatic choice of the default operating system without different instructions from the user.
By clicking on Advanced settings, you can, for example, change the labels (operating system names) displayed in the start menu.
Make any Operating System Bootable With EasyBCD
If other operating systems are installed on the system, they can be made bootable by clicking on the Add a new entry button and selecting the product to boot (Windows, Linux, macOS,…).
By indicating the unit or partition where the operating system has been installed, EasyBCD will add the appropriate entries in the BCD file (Add entry).
In this way also other operating systems, other than Windows, can be started with the Microsoft boot manager.
Note that EasyBCD also allows booting of older Windows operating systems that are no longer supported by Microsoft (e.g. Windows 2000).
System Boot From an ISO Image
Few people know that the system can also be booted from an ISO or VHD image.
Suppose you often use some tools for system maintenance: it might make sense to store it on an ad hoc disk partition then use EasyBCD to add a command to the boot menu for loading the utility.
Instead of inserting a USB stick, then, thanks to EasyBCD you can load the contents of an ISO or VHD file from the boot menu when the system is turned on.
To proceed, simply click on Add an entry and, in the case of bootable files in ISO format (in the article Rufus, guide to using the program to create bootable media you can find different information on the ISO format), select the ISO card and then set the file to be started in the Path box (in the example we asked you to insert in the Windows boot menu the Windows PE environment created with Macrium Reflect Free: Backup with Macrium Reflect Free 7: how to copy data safely).
The advice is to request, where possible, the loading in memory of the operating system, especially in the case of lighter tools.
After clicking on Add entry, you will find the entry that allows loading the contents of the ISO file in the View settings section of EasyBCD.
When the system is restarted, you can comfortably choose whether to boot the main operating system or, in our case, the Macrium Reflect maintenance and recovery environment.
A good idea would be, as we proposed earlier, to create a partition dedicated to storing ISO files with the maintenance tools you intend to add to the Windows boot menu.
To proceed, just run Disk Management from Windows environment (Windows+R,diskmgmt.msc) select the hard disk, right-click it and choose Reduce volume.
In the example we asked to reduce the size of the main hard disk by 100 GB.
From EasyBCD, in case you want to delete a boot entry, references to ISO and VHD files included, just click on the Edit boot menu button, highlight the entry to remove then choose Delete.