Set up multiple boot machines (with Linux and other operating systems)

Article Title: Set up a multi-boot machine (with Linux and other operating systems ). Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source.
Most of the instructions that enable computers to guide multiple operating systems are similar to Steve Martin's joke about how to get $1 million free of charge. (Step 1: get $1 million ). Many planning steps and initial requirements are ignored or only slightly mentioned. This article explains all the planning and settings required before installing the multi-boot system.
　　
　　 Before getting started
To install multiple operating systems on a computer, you must understand the details of the hard disk organization. Readers familiar with the boot process, Hard Drive format, and partition can directly jump to step 1.
　　
　　 What is a partition?
Partition is the physical part of the drive. You can format the partition logic into the desired file system, or use it to create further logical parts. There are three types of partitions: Master, extension, and logic. A drive can have up to four primary partitions. The primary partition cannot be divided into smaller units. It is mainly used to install the operating system. Extended partitions are also primary partitions. It differs from the primary partition in that it has an extended function that can be divided into logical partitions. This allows the drive to be organized into multiple logical parts that exceed the limits of four primary partitions. Each partition can be logically formatted to support the file systems required by a specific operating system.
　　
　　 Guiding Process
The "boot" process comes from the word "boot. It is a kind of operation that relies on your own efforts to achieve success. The actual situation is that when the computer is turned on, the CPU runs the Boot Code implanted into the system rom bios (read-only memory Basic Input and Output System. The Startup Program contains the code for testing the computer and setting the hardware to be used. The last step is to mount and run the program stored on the first sector of the first drive. This is the primary Boot Record (MBR), which is the primary Boot Program (MBP ). Check where the primary partition is and which primary partition is an active partition. The active partition has its own Boot Record and contains a program designed to start the operating system on the partition. Partition Boot records are usually called Partition Boot superblocks.
　　
Step 2: Back up all content!
This is important: Spend some time backing up all files on the drive when making important configuration changes to the boot process. The subsequent steps will change the basic method for attaching an operating system to a computer. If an error occurs, the hard disk cannot be accessed and files may not be restored. If you have enough disk space, it is best to back up the entire drive image. If you do not have enough space, you must at least back up data files that cannot be easily regenerated, such as resumes, images, databases, and accounting files.
　　
Step 2: confirm the old and new OS media and create a boot floppy disk
After backing up all important files and making changes, make sure that you have the complete existing operating system and new operating system source disks on hand. This includes updates, patches, utilities, and service release software. They should all be on an easy-to-access medium. Ease of access means loading is possible without complex driver settings. Floppy disk is the best choice. The most frustrating thing is that, when half of the files were installed, they found that the release files on the floppy disk were old versions, but the new versions were not accessible on hard drive; or your cousin Vicky borrowed the latest kernel release CD, and you will be in trouble until she comes back from camp.
　　
Before changing the hard disk, make sure that you have a boot floppy disk with the utilities required to recover the drive in case of a problem. New Linux users often encounter problems when installing Linux on machines with windows 95 installed. The Linux installation process starts well, but when you ask whether you want to install LILO (Linux Loader Program), problems may occur. Instead of placing LILO in the new Linux logical partition superblock, the user puts LILO in the Master Boot Record. Linux and Windows 95 are unavailable when you reboot your computer. The solution is to use WIN95 with FDISK. EXE to start a floppy disk. After the floppy disk is started, issue the command FDISK/MBR to restore the Master Boot Record from the copy made by LILO.
　　
Step 2: repartition the drive
Different operating systems have different restrictions on how to install and where to install on the hard disk. Linux may be the most suitable OS for multi-boot systems. It can be booted from the primary partition and logical partition, or from the secondary hard drive. Other operating systems have limited capabilities in terms of partition types and locations. The most common limit is the offset allowed at the beginning of the shard superblock. In some cases, this limit is placed at the 1,024th cylindrical boundary of the hard drive. This depends on the size and type of the hard drive, the file format, the computer BIOS, and the operating system itself.
　　
　　 Partition requirements for some operating systems
　　
Considering the flexibility of Linux and the restrictions of other operating systems, it is best to place Linux in a logical partition and a secondary hard drive (if any ). This allows you to use other operating systems most flexibly and allows Linux to retain MBR for use by other operating systems.
　　
Pay attention to several issues when creating or modifying hard drive partitions. Linux has FDISK and Disk Druid programs. Make sure that you have the latest version. Earlier versions may cause other operating systems to be unable to read partition tables. The new versions of Linux FDISK and Disk Druid do not cause this problem. Business programs are more powerful, allowing you to move, change, merge, and reformat partitions, and create and delete partitions. One of the best commercial applications is PowerQuest's Partition Magic. This program runs in Windows and Linux and allows almost all changes to the hard drive without affecting the operating system, programs, and data on the drive.
　　
Step 2 (last step): Configure OS Selection
There are three methods to manage the operating system:
　　
　　 Use the bootstrap Manager
Configure the OS-managed dual-boot System
Use a utility to mark a partition as active or manually edit the primary Boot Record to manually set the OS to active ".
　　
The bootstrap manager provides menu options for maximum flexibility and ease of use. This program is installed in the MBR of the master hard drive. to replace it, simply select the active partition and load the OS boot program from the root super block. The two programs that can be done in this way are IBM Boot Manager and PowerQuest BootMagic.
　　
You can use the LILO and Windows NT boot loaders in Linux to create a Dual Boot configuration. You can change the OS loader so that the OS can be selected alternately when it is started. This works well without buying other software. Requires a moderate level of technical knowledge to reconfigure the OS loader to load the operating system alternately. For more information, see references.
　　
The dos fdisk or PowerQuest PQBoot command line utility can change the active partition attributes so that OS can be mounted to the selected active partition on the first physical hard disk. This is a useful method for those who only want to occasionally change the operating system. But it does have restrictions: You can only select the primary partition of the first hard drive.
　　
　　 Hardware-based options
Instead of creating new partitions and setting the complexity of OS boot selection, reconfigure the computer to boot from other media than the hard disk. Most modern computers can be configured in BIOS configuration so that boot not only from a floppy disk, but also from a cd rom drive and SCSI device. Which programs can run in this way have certain restrictions and are often technically difficult.
　　
Linux and other operating systems released through cd rom can boot from the cd rom drive, but there are some restrictions. There is no Windows version that can be booted from cd rom because it is a read-only device.
　　
Floppy Disk boot is slow, but flexible. If you usually run Linux but occasionally use Windows NT, You Can format a floppy disk in NT and use the NT boot file NTLDR and NTDETECT. COM and BOOT. copy INI to this floppy disk to create an NT boot disk. When the computer boots, it finds the NT partition and loads it into NT.
　　
If you can afford it and the computer supports it, an excellent way is to boot from large-capacity removable media such as Iomega Zip or Jazz drives. You only need to change the portable disk to change the OS.
　　
Swap hard drive is the highest level of hardware-based OS selection. The disadvantage is that the cost is very expensive.
　　
　　 Conclusion
The ability to select from two or more operating systems during boot will save the cost of running another operating system on the second machine or the time required to delete and reinstall the new OS. Changing a machine to allow the selection of multiple operating systems involves a lot of work: Changing the partition of a hard drive, adding or changing software, and changing the Master Boot Record. This software method is complex, but it can still be managed after proper planning. It also has the advantages of low price or even free of charge.
　　
Hardware solutions that use removable or interchangeable media are simple but expensive. Boot from a floppy disk or cd rom is slow and has restrictions.