Multi-boot system

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A multiboot or multi-boot system is a computer on which two or more operating systems are installed in parallel. A computer with two systems installed in parallel is also known as a dual-boot system .

The installation is therefore also referred to as a multiboot installation .

The operating systems are installed on different volumes , such as either different partitions of a data store or on different physical data stores such as hard drives. The only requirement is that the user can select the operating system to be started via a boot menu . Multiboot-capable systems can either already support this function in the firmware or a. if the firmware does not support this, generate a boot menu on a bootable medium using an upstream boot loader .

Working principle

Multiboot systems require a user who makes a selection about the operating system to be started. However, most multi-boot configurations also see a default setting ( English default ) after a specified timeout automatically starts a previously selected operating system.

Multiboot installations are heavily dependent on the respective computer system. These are also referred to as the computer platform , which includes the processor architecture used , the firmware implemented and the operating systems available for it. Platforms that enable a boot menu in the firmware are e.g. B. Macs from 1998 with PowerPC processors ( New World Macs), their successors from 2006 with Intel processors and all PCs with UEFI as firmware.

Regardless of the firmware, a boot menu can also be implemented using a boot loader . Here starts the firmware to the respective boot loader from a bootable disk, such as a hard drive or SSD , as if this would be to be launched operating system. The bootloader then takes on the function of a boot menu. Such bootloaders usually offer additional functions, such as starting additional start configurations that are not supported by the firmware, or loading configuration data. More powerful boot loaders are therefore also known as boot managers .

Even standard bootloaders from common operating systems often offer (limited) multiboot functionality. For example, the Windows boot loader NTLDR and its successor Bootmgr can start several Windows operating systems installed in parallel. Linux boot loaders such as LILO or GRUB can traditionally start a large number of operating systems and are also used on other Unix-like operating systems, e.g. B. BSD or OpenSolaris .

Reasons for establishment


With a multiboot system, access can be made via another, separately installed system (also on the same hard disk). There are live systems in which hard disk access is blocked until the user has explicitly given write access to one or more storage media. If the Internet is used via another system, malicious programs have no chance of infecting the main system. This minimizes the risk of opening e-mails because the computer usually only accesses the system that is currently running (on a separate partition or hard drive). In the case of a live system, only the main memory that is deleted after the restart can theoretically be infected.

Experimental system

A multi-boot system can consist of different operating systems or, for example, several identical Windows versions can be installed side by side in parallel. For example, to experiment with different registry settings.


Diversity of user software

An operating system with different version numbers can also be set up as a multi-boot system. Windows 7 can be installed together with Windows XP on a computer so that older software can continue to be used.

A multi-boot system is often set up in order to be flexible in the selection of the application software. Some programs are limited to one platform or a few operating systems, so a multi-boot solution offers more choice. The selection of widespread, commercial products for the Windows operating system is very large, so that users of other operating systems have more options thanks to a multi-boot system. As an example, there is Boot Camp for Apple Macbooks and iMacs, with which Windows can be installed alongside MacOS.

Diverse application possibilities

PC systems with preconfigured multi-boot systems are available in stores. Notebooks with pre-installed Windows can optionally also be started up with another operating system that was also pre-installed. A simple, fast-booting operating system variant (such as Windows 10 mini) is often used here in order to provide a quick solution for smaller tasks such as checking e-mails. The more extensively configured main system can then be booted for more demanding, complex tasks. For this solution, the option of separate activation options is often chosen for each system.

Another possibility is to use a notebook or netbook for different areas of application. At home, a suitably configured system can serve as a hardware firewall or as a print server , for example , while another operating system can turn the same device into a mobile Internet PC while on the move.


Virtual solutions can quickly bring the computer to its performance limits, especially with less powerful hardware, and run slowly because, in addition to the actual operating system, the system in the virtually installed environment requires additional performance. A multi-boot system can be the better choice depending on the application and hardware requirements.


AMD and Intel (except Apple-Mac) based systems

If another operating system is to be installed in addition to a Windows version, Windows should be installed first. In many complete PCs, it is often already pre-installed anyway. The second step is to install another operating system, such as GNU / Linux , Solaris , FreeBSD , etc. If several versions of Windows are to be installed, start with the oldest.

Each operating system is installed on a separate partition. When installing all systems on one hard drive, the required partition is either created in advance of the installation or, depending on the installation tool used, can also be created during the installation. Then an existing hard disk partition is shrunk. The partition for the planned installation can be on another hard drive. With many modern distributions such as Debian GNU / Linux , Mandriva , Fedora , Pardus , openSUSE , the partitioning of the hard disk is suggested by the system. This suggestion will be implemented automatically on request or can be manually adapted to your own needs.

Automatic detection of other operating systems occurs often, but not always. Operating systems that are not recognized can be added to the boot loader after installation, with openSUSE using the YaST configuration tool .

Operating systems are often installed that require different file systems for installation, for example Windows NT -based Windows versions with the NTFS file system and Linux with file systems such as ext4 or Btrfs . It is important to ensure that partitions to be used jointly are formatted with a file system supported by both systems so that they can be accessed from both systems.

Apple Mac with Intel processors

With the Apple software Boot Camp different Windows versions can be installed on Apple Mac computers with Intel processors. Only a dual boot variant is officially supported, i.e. a Windows version in addition to macOS . However, multi-boot variants with more than two operating systems are also possible.

If Windows is selected in the Boot Camp menu after the start, it starts natively. However, it is not always possible to install Windows in UEFI mode. The Apple-specific EFI offers the BIOS emulation mode CSM for Windows, so that the MBR partition table must be used for Windows , while the GUID partition table is used for macOS in EFI mode . Boot Camp sets up a hybrid partition table for this, but it is limited to four partitions. By using a second physical data storage device, for example a second hard disk or SSD, this limitation can be circumvented relatively easily.

Multiboot USB sticks

USB sticks are also suitable for installing different operating systems on them at the same time. As a result, every computer that is booted from such a USB stick temporarily becomes a multiboot system. The prerequisite for using a (multi) boot USB stick is that the PC can be booted from USB.

Such a USB stick can - depending on the desired area of ​​application - hold a wide variety of systems ready for booting:

  • System administration:
    • Diagnosis: Hardware check (e.g. main memory: memcheck)
    • Error correction: e.g. B. Correct hard drive errors
    • Virus protection
    • Configuration: e.g. B. hard disk partitioning (e.g. gparted )
    • Systems to attempt to recover lost or unavailable passwords
  • Mobile office: If portable applications are installed on the same USB stick , you can work with these applications from any PC that can be booted via USB and you will always find your own, familiar working environment. Although portable applications can also be transported on normal USB sticks, one then has to rely on a suitable operating system being available on the existing PC. If a (multi) boot USB stick is used instead, you definitely have the right operating system at hand.
  • Entertainment:
    • Multimedia operating systems optimized for playing music and films
    • Emulators
  • Systems that are optimized for Internet browsing

Many other application scenarios are conceivable.


  • Thorsten Leemhuis: Paths to Coexistence. Install Linux and Windows together . ct 2/2005. P. 80ff.

Individual evidence

  1. Archived copy ( memento of the original from April 6, 2017 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot /
  4. Archived copy ( memento of the original from April 6, 2017 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot /
  5. Hardware revolution: Apple opens Mac computers for Windows . In: Spiegel Online . April 5, 2006 ( [accessed September 8, 2019]).

Web links