Linux基础教程学习笔记24——磁盘、分区和文件系统管理
一、MBR主引导记录
MBR有512个字节，分为三个部分：第一部分446个字节，存储了引导分区；第二部分64字节为分区表；第三部分2个字节结束符；
每个分区需16个字节，所以MBR的模式下只能划分4个主分区或3个主分区和扩展分区；主分区可以直接使用，扩展分区不能直接使用，在扩展分区上划分逻辑分区再使用；
[root@linuxidc ~]# cat /proc/partitions
major minor #blocks name
2 0 4 fd0
8 0 20971520 sda
8 1 512000 sda1
8 2 20458496 sda2
11 0 3655680 sr0
253 0 18358272 dm-0
253 1 2097152 dm-1
二、GPT
GPT可以记录128个主分区；
三、使用命令管理磁盘分区
1、fdisk命令
使用fdisk划分磁盘，默认会划分为MBR格式的磁盘：
fdisk -l 查看当前的磁盘和分区情况：
[root@linuxidc ~]# fdisk /dev/sdb
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0xac4a9d92.
Command action
a toggle a bootable flag
b edit bsd disklabel
c toggle the dos compatibility flag
d delete a partition 删除分区
g create a new empty GPT partition table
G create an IRIX (SGI) partition table
l list known partition types 列出分区类型
m print this menu 打印帮助菜单
n add a new partition 添加一个新分区
o create a new empty DOS partition table
p print the partition table 打印分区表
q quit without saving changes
s create a new empty Sun disklabel
t change a partition's system id
u change display/entry units
v verify the partition table
w write table to disk and exit 退出并保存，然后使用partprobe或partx /dev/sdX刷新
x extra functionality (experts only)
添加分区：
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p): p
Partition number (1-4, default 1):
First sector (2048-10485759, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-10485759, default 10485759): +1G
Partition 1 of type Linux and of size 1 GiB is set
Command (m for help): p
Disk /dev/sdb: 5368 MB, 5368709120 bytes, 10485760 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0xac4a9d92
Device Boot Start End Blocks Id System
/dev/sdb1 2048 2099199 1048576 83 Linux
只能划分四个主分区，如果要划分多余四个分区，则需要在第四个分区创建扩展分区，在扩展分区上创建逻辑分区：
Device Boot Start End Blocks Id System
/dev/sdb1 2048 2099199 1048576 83 Linux
/dev/sdb2 2099200 4196351 1048576 83 Linux
/dev/sdb3 4196352 6293503 1048576 83 Linux
/dev/sdb4 6293504 10485759 2096128 5 Extended
/dev/sdb5 6295552 6500351 102400 83 Linux
有*标识代表的是启动分区：
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 1026047 512000 83 Linux
/dev/sda2 1026048 41943039 20458496 8e Linux LVM