磁盘分区知识点

1.MBR 主引导记录

位置在磁盘的开头 0磁头0磁道1扇区512字节前446字节

磁盘MBR分区

2.分区类型

主分区：1个主分区要占用16字节的分区表，在一个磁盘中最多4个主分区
扩展分区：扩展分区无法直接使用，数据必须放在扩展分区中的逻辑分区，一个扩展分区占用16字节的分区表，1个磁盘中只能创建1个扩展分区
逻辑分区：需要先创建扩展分区，存放数据，最多11个

3.分区的命名规则

硬盘名字：sata、sas、scsi
/dev/sd？？？
/dev/sda第一块硬盘
/dev/sdd第四块硬盘
云服务器（阿里云）/dev/vda
/dev/vdb
分区名字：
主分区或扩展分区：1-4 /dev/sda1 /dev/sda4
逻辑分区:从5开始（>=5）
/dev/sda5

4.分区实战

分区命令

fdisk
-l查看磁盘分区信息
p显示磁盘分区信息
n创建分区
d删除磁盘分区
w保存并退出
q或ctrl+c退出不保存t改变分区的类型

[root@oldboy59 ~]# fdisk -l /dev/sdb

Disk /dev/sdb: 106 MB, 106954752 bytes, 208896 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: 0x06b298c4

   Device Boot      Start         End      Blocks   Id  System
第1个里程碑-创建分区
[root@oldboy59 ~]# 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.


Command (m for help): n
Partition type:
   p   primary (0 primary, 0 extended, 4 free)
   e   extended
Select (default p): 
Using default response p
Partition number (1-4, default 1): 
First sector (2048-208895, default 2048): 
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-208895, default 208895): 
Using default value 208895
Partition 1 of type Linux and of size 101 MiB is set

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.
第2个里程碑-格式化  创建文件系统 mkfs  make filesystem 
▽root@oldboy59 ~]# mkfs.xfs /dev/sdb1
meta-data=/dev/sdb1              isize=512    agcount=4, agsize=6464 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0, sparse=0
data     =                       bsize=4096   blocks=25856, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal log           bsize=4096   blocks=855, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
第3个里程碑-挂载
[root@oldboy59 ~]# mount /dev/sdb1  /mnt/
[root@oldboy59 ~]# df -h 
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda3        20G  1.9G   18G  10% /
devtmpfs        980M     0  980M   0% /dev
tmpfs           991M     0  991M   0% /dev/shm
tmpfs           991M  9.6M  981M   1% /run
tmpfs           991M     0  991M   0% /sys/fs/cgroup
/dev/sda1       197M  105M   93M  54% /boot
tmpfs           199M     0  199M   0% /run/user/0
/dev/sdb1        98M  5.3M   93M   6% /mnt

永久生效第4个里程碑-永久挂载

[root@oldboy59 ~]# vim /etc/fstab 

#
# /etc/fstab
# Created by anaconda on Tue Mar 26 11:36:14 2019
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
UUID=15513b41-8012-4f6c-83eb-c27a49d401ab /                       xfs     defaults        0 0
UUID=17b0ef4d-c758-4707-aa49-f771c938e3b4 /boot                   xfs     defaults        0 0
UUID=0abead87-ef0e-4bd8-ac6b-b5509512907e swap                    swap    defaults        0 0
/dev/sdb1                                 /mnt                   xfs     defaults        0 0 
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"/etc/fstab" 12L, 595C written

parted

parted （实时生效）
p print 显示磁盘信息
mktable mklabel make partition table 创建磁盘分区表 MBR GPT
mkpart make partition 创建磁盘分区
rm 删除磁盘分区
q quit 退出磁盘分区

[root@oldboy59 ~]# parted /dev/sdc
GNU Parted 3.1
Using /dev/sdc
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) p                                                                
Error: /dev/sdc: unrecognised disk label
Model: VMware, VMware Virtual S (scsi)                                    
Disk /dev/sdc: 107MB
Sector size (logical/physical): 512B/512B
Partition Table: unknown
Disk Flags: 
(parted)                                                                  
(parted) mk                                                               
mklabel  mkpart   mktable  
(parted) mk
mklabel  mkpart   mktable  
(parted) mktable gpt
(parted) p                                                                
Model: VMware, VMware Virtual S (scsi)
Disk /dev/sdc: 107MB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: 

Number  Start  End  Size  File system  Name  Flags

(parted) mkpart primary 0 10
Warning: The resulting partition is not properly aligned for best performance.
Ignore/Cancel? i                                                          
(parted) p                                                                
Model: VMware, VMware Virtual S (scsi)
Disk /dev/sdc: 107MB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: 

Number  Start   End     Size    File system  Name     Flags
 1      17.4kB  10.0MB  9983kB               primary

(parted) q                                                                
Information: You may need to update /etc/fstab.

/etc/fstab

Welcome to emergency mode 欢迎进入紧急模式/维护模式
磁盘故障或/etc/fstab
Give root password for manintenance
给出root密码进入维护模式
(或按ctrl +d 继续 )

fdisk & parted
共同 磁盘分区 磁盘分区
区别 支持2TB以内硬盘 大于2TB磁盘
支持MBR分区表 MBR GPT（支持更大的硬盘和更多的主分区）

primary 主分区
extended 扩展分区
logical 逻辑分区
partition 分区
partition table 分区表