1. Abstract
Under normal circumstances, our laptops or work computers are installed with Windows divided into several areas by default. Currently, it is win7, win8, win 10, win11, etc. Suddenly we have a need to install centos. What should we do next? What are the key points? Do I have to follow the online posts step by step?
No, in fact, I think, just remember one thing, disk space, free disk
2. Key points
1. Go to My Computer->Management->Disk Management on Windows to compress a part of the previously divided area, or compress a part of each of the multiple divided areas.
2. Prepare ubunntu or centos USB boot disk
3. Set bios to boot from ubuntu USB disk or centos USB disk
Follow the prompts to find the location where the hard disk is allocated, and use a free hard disk partition or set a mount point to successfully install dual systems, triple systems, etc.
During the process, you can take photos and remember the sizes of each partition. Do not occupy the window partitions.
If you use multiple systems, remember not to occupy or recycle multiple partitions of the previous Linux. Don't be afraid of too many partitions. Remember that only the free ones can be used and there will be no mistakes.
3. Important screenshots
It can be used after compression. How to compress reference:
Only the free ones can be used by you. Please refer to them when using them.
磁盘分区 ，我们点击空余空间，点 + 号新建分区。这里我们简单分四个区域就行，
分别是
/ ：主分区，根目录整个系统的大区域一般15G以上,若需要安装的东西较多建议分大点。
/boot ：主分区，启动目录，开机启动所需目录。（200M-2G）
swap ：逻辑分区，交换空间，一般和物理内存一样就行。
/home ：逻辑分区，home目录，就是我们自己存放用户数据的目录。一般有多少给多少
这里简要介绍下 swap 交换空间的作用：swap 交换空间主要涉及到 虚拟内存 的概念，是由处理器中的 内存管理单元（MMU）控制的。我们知道，物理内存的大小是受限的，但是我们为什么有时候可以开很多应用，甚至有时这些应用使用的内存空间大于实际的物理内存空间，这时就是因为 swap 空间的存在，MMU会把那些暂时用不着的已打开的应用暂时从内存空间移到硬盘中去，也就是我们说的 swap 空间，用的时候再从 swap 空间挪回来，这样就可以高效地利用物理内存空间了。所以 swap 到底给多大取决于你系统的应用场景。
首先找到 free space 空间，如下，选中该空间，点击左下角的加号+，进行内存分配
The above list is the actual boot menu of window7, centos 7, and ubuntu 16.04 installed on a physical machine at the same time. The three systems can work independently.
3. Summary:
Before doing the actual operation, you must first understand the key points. This will save you a lot of confusion. Here is a memo, and I hope it can help everyone!