linux磁盘分区、挂载

磁盘概述

https://www.cnblogs.com/zh-dream/p/11727902.html

Linux分区表格式和文件系统类型

linux磁盘分区表格式分为两种：

• MBR

　　最多支持四个主分区、系统只能安装在主分区、扩展分区要占一个主分区、MBR最大支持2TB，但拥有最好的兼容性

• GPT

　　大于2TB时使用，支持无限多个主分区（说是这么说，但是操作系统可能会限制，比如Windows下最多128个分区）、最大支持18EB的大容量

查看分区表格式 fdisk -lu <设备名>

如果System="Linux"，说明是MBR分区表格式

如果System="GPT"，说明是GPT分区表格式

[root@master ~]# fdisk -lu /dev/sdb

Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 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: 0x45ef390c

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048     4196351     2097152   83  Linux

Linux常见文件系统类型

（1）ext

（2）xfs

使用blkid命令查看以分区的磁盘文件系统类型 

• blkid  <以分区设备的磁盘名称>

[root@master ~]# blkid /dev/sda1
/dev/sda1: UUID="bba2c917-8540-41c8-97e6-f1d73d9143ba" TYPE="xfs" 

添加磁盘

查看新添加的磁盘

[root@master ~]# lsblk -f           ##查看磁盘分区信息
NAME FSTYPE LABEL UUID MOUNTPOINT
sda 
├─sda1 xfs bba2c917-8540-41c8-97e6-f1d73d9143ba /boot
├─sda2 swap 1c0f8351-49f0-4dd8-9a8b-1aff1d4a77b0 [SWAP]
└─sda3 xfs 0bbd5e50-606c-4c47-8cd7-1ae67f812437 /
sdb                                  ##新添加的磁盘
sdc 
├─sdc1 xfs da38abcd-a06e-4ef1-93fa-49a5b8773f01 
└─sdc2      
sr0 iso9660 CentOS 7 x86_64 2018-05-03-21-07-04-00

[root@master ~]# ll /dev/sd
sda   sda1  sda2  sda3  sdb   sdc   sdc1  sdc2  

fdisk命令对新磁盘进行分区

用法

fdisk [options] <disk> change partition table                  ##修改分区表
fdisk [options] -l <disk> list partition table(s)              ##查看分区表
fdisk -s <partition> give partition size(s) in blocks          ## 指定分区块大小

常用选项

选项	含义
-b <size>	扇区大小，默认512bytes，可选值(512, 1024, 2048 or 4096)
-l	查看分区信息
-u[=<unit>]	显示每个柱面和扇区的大小
-h	查看帮助

查看分区信息

[root@master ~]# fdisk -l

Disk /dev/sda: 107.4 GB, 107374182400 bytes, 209715200 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: 0x000bdcb7

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
/dev/sda2         2099200     4196351     1048576   82  Linux swap / Solaris
/dev/sda3         4196352   209715199   102759424   83  Linux

Disk /dev/sdc: 21.5 GB, 21474836480 bytes, 41943040 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: 0xeed0d630

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1            2048    10487807     5242880   83  Linux
/dev/sdc2        10487808    14682111     2097152   83  Linux

查看某块盘分区信息

[root@master ~]# fdisk -l /dev/sda

Disk /dev/sda: 107.4 GB, 107374182400 bytes, 209715200 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: 0x000bdcb7

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
/dev/sda2         2099200     4196351     1048576   82  Linux swap / Solaris
/dev/sda3         4196352   209715199   102759424   83  Linux

显示柱面单位大小

[root@master ~]# fdisk -u=cylinders -l  /dev/sda

Disk /dev/sda: 107.4 GB, 107374182400 bytes, 209715200 sectors
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000bdcb7

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1         131     1048576   83  Linux               
/dev/sda2             131         262     1048576   82  Linux swap / Solaris
/dev/sda3             262       13055   102759424   83  Linux

开始分区

新添加的盘是无法识别到的，需要重启

[root@master ~]# ll /dev/sd
sda   sda1  sda2  sda3  sdb   sdc   sdc1  sdc2  

[root@master ~]# fdisk /dev/sdb
fdisk: cannot open /dev/sdb: No such file or directory

[root@master ~]# fdisk /dev/sdc 
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): m             ## 打印帮助
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                ## 创建一个空GPT分区表
   G   create an IRIX (SGI) partition table
   l   list known partition types                             ## 查看可用分区类型
   m   print this menu
   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
   q   quit without saving changes                            ## 退出不保存分区信息
   s   create a new empty Sun disklabel
   t   change a partition's system id
   u   change display/entry units                             ## 以柱面为单位显示（已遗弃）
   v   verify the partition table
   w   write table to disk and exit                          ## 保存分区信息并退出
   x   extra functionality (experts only)

开始分区

[root@master ~]# 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): p       

Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 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: 0x45ef390c

   Device Boot      Start         End      Blocks   Id  System

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 (2048-41943039, default 2048):                                         ## 初始扇区必须是2048的倍数，即2048*512/（1024*1024）=1M，因为EFI，这部分空间是留给EFI的引导代码
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-41943039, default 41943039): +2G         ## 分区是按照扇区分的，也可以指定大小
Partition 1 of type Linux and of size 2 GiB is set

Command (m for help): p

Disk /dev/sdb: 21.5 GB, 21474836480 bytes, 41943040 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: 0x45ef390c

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048     4196351     2097152   83  Linux

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

Calling ioctl() to re-read partition table.
Syncing disks.

通知内核分区表的变化

[root@master ~]# partprobe /dev/sdb

检查分区信息

[root@master ~]# lsblk -f
NAME   FSTYPE  LABEL           UUID                                 MOUNTPOINT
sda                                                                 
├─sda1 xfs                     bba2c917-8540-41c8-97e6-f1d73d9143ba /boot
├─sda2 swap                    1c0f8351-49f0-4dd8-9a8b-1aff1d4a77b0 [SWAP]
└─sda3 xfs                     0bbd5e50-606c-4c47-8cd7-1ae67f812437 /
sdb                                                                 
└─sdb1                                                              
sdc                                                                 
├─sdc1 ext4                    9399025f-d5ca-4951-b90a-92e5141f7e7d 
└─sdc2                                                              
sr0    iso9660 CentOS 7 x86_64 2018-05-03-21-07-04-00         

创建文件系统

[root@master ~]# mkfs.xfs /dev/sdb1
meta-data=/dev/sdb1              isize=512    agcount=4, agsize=131072 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0, sparse=0
data     =                       bsize=4096   blocks=524288, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal log           bsize=4096   blocks=2560, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0

挂载

[root@master ~]# mount /dev/sdb1 /data
[root@master ~]# df -h
Filesystem      Size  Used Avail Use% Mounted on
devtmpfs        901M     0  901M   0% /dev
tmpfs           911M  8.0K  911M   1% /dev/shm
tmpfs           911M  9.6M  902M   2% /run
tmpfs           911M     0  911M   0% /sys/fs/cgroup
/dev/sda3        98G  2.5G   96G   3% /
/dev/sda1      1014M  135M  880M  14% /boot
tmpfs           183M     0  183M   0% /run/user/0
/dev/sdb1       2.0G   33M  2.0G   2% /data

写入到 /etc/fstab

将挂载信息写入到 /etc/fstab中，以便系统启动时自动挂载，不用每次手动挂载

查看UUID

[root@master ~]# blkid /dev/sdb1
/dev/sdb1: UUID="6cfbe843-e280-4d85-9ae3-60b0ebcc5909" TYPE="xfs" 

写入 /etc/fstab

[root@master ~]# echo "UUID=6cfbe843-e280-4d85-9ae3-60b0ebcc5909 /data xfs defaults 0 0" >> /etc/fstab 

重启后查看

[root@master ~]# df -h
Filesystem      Size  Used Avail Use% Mounted on
devtmpfs        901M     0  901M   0% /dev
tmpfs           911M  8.0K  911M   1% /dev/shm
tmpfs           911M  9.6M  902M   2% /run
tmpfs           911M     0  911M   0% /sys/fs/cgroup
/dev/sda3        98G  2.5G   96G   3% /
/dev/sdb1       2.0G   33M  2.0G   2% /data
/dev/sda1      1014M  124M  891M  13% /boot
tmpfs           183M     0  183M   0% /run/user/0
[root@master ~]# ll /data/
total 0

 使用设备名和label及uuid作为标识的不同

使用设备名称（/dev/sda)来挂载分区时是被固定死的，一旦磁盘的插槽顺序发生了变化，就会出现名称不对应的问题。因为这个名称是会改变的。
不过使用label挂载就不用担心插槽顺序方面的问题。不过要随时注意你的Label name。至于UUID，每个分区被格式化以后都会有一个UUID作为唯一的标识号。使用uuid挂载的话就不用担心会发生错乱的问题了。