跳到主要内容

fdisk

查看磁盘使用情况和磁盘分区

补充说明

fdisk命令 用于观察硬盘实体使用情况,也可对硬盘分区。它采用传统的问答式界面,而非类似DOS fdisk的cfdisk互动式操作界面,因此在使用上较为不便,但功能却丝毫不打折扣。

语法

$ fdisk <选项> <参数>

查询选项

  • -l: 查询本机可以识别的硬盘和分区
  • -l <盘符>: 观察硬盘实体使用情况

设置选项

危险

fdisk 设置选项千万要谨慎操作,以防把系统文件或重要盘符删除

  • -b <大小>: 设置可引导标记,扇区大小(512、1024、2048或4096)
  • -c[=<模式>]: 设置 DOS 操作系统兼容标记,兼容模式:“dos”或“nondos”(默认)
  • -h: 打印此帮助文本
  • -u[=<单位>]: 显示单位:“cylinders”(柱面)或“sectors”(扇区,默认)
  • -v: 打印程序版本
  • -C <数字>: 指定柱面数
  • -H <数字>: 指定磁头数
  • -S <数字>: 指定每个磁道的扇区数

参数

设备文件:指定要进行分区或者显示分区的硬盘设备文件。

实例

首先选择要进行操作的磁盘:

root@lectcode:/ # fdisk /dev/vda1

Welcome to fdisk (util-linux 2.31.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

The old ext4 signature will be removed by a write command.

Device does not contain a recognized partition table.
Created a new DOS disklabel with disk identifier 0x9e593554.

Command (m for help): m # 列出盘符操作可使用的所有指令

Help:

DOS (MBR)
a toggle a bootable flag,切换可引导标志,设定硬盘启动区
b edit nested BSD disklabel,编辑嵌套的BSD磁盘标签
c toggle the dos compatibility flag,切换dos兼容性

Generic,基础指令
d delete a partition,删除硬盘分割区属性
F list free unpartitioned space,列出可用的未分区空间
l list known partition types,列出已知分区类型
n add a new partition,设定新的硬盘分割区
p print the partition table,显示硬盘分割情形
t change a partition type,改变硬盘分割区属性
v verify the partition table,验证分区表
i print information about a partition,打印有关分区的信息

Misc,其他
m print this menu,列出盘符操作可使用的所有指令
u change display/entry units,更改显示/输入单位
x extra functionality (experts only),扩展应用,高级功能

Script
I load disk layout from sfdisk script file,加载 [sfdisk](/linux-command/disk-maintain/sfdisk) 磁盘布局脚本
O dump disk layout to sfdisk script file,将磁盘布局转为 [sfdisk](/linux-command/disk-maintain/sfdisk) 脚本

Save & Exit
w write table to disk and exit,结束并写入硬盘分割区属性
q quit without saving changes,结束不存入硬盘分割区属性

Create a new label
g create a new empty GPT partition table,创建新的空GPT分区表
G create a new empty SGI (IRIX) partition table,创建新的空SGI(IRIX)分区表
o create a new empty DOS partition table,创建新的空DOS分区表
s create a new empty Sun partition table,创建新的空Sun分区表

Command (m for help): 继续输入需要的指令

输入 p 列出磁盘目前的分区情况:

Command (m for help): p

Disk /dev/sdb: 3221 MB, 3221225472 bytes
255 heads, 63 sectors/track, 391 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sdb1 1 1 8001 8e Linux LVM
/dev/sdb2 2 26 200812+ 83 Linux

输入 d 然后选择分区,删除现有分区:

Command (m for help): d
Partition number (1-4): 1

Command (m for help): d
Selected partition 2

查看分区情况,确认分区已经删除:

Command (m for help): print

Disk /dev/sdb: 3221 MB, 3221225472 bytes
255 heads, 63 sectors/track, 391 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System

Command (m for help):

输入 n 建立新的磁盘分区,首先建立两个主磁盘分区:

Command (m for help): n
Command action
e extended
p primary partition (1-4)
p //建立主分区
Partition number (1-4): 1 //分区号
First cylinder (1-391, default 1): //分区起始位置
Using default value 1
last cylinder or +size or +sizeM or +sizeK (1-391, default 391): 100 //分区结束位置,单位为扇区

Command (m for help): n //再建立一个分区
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 2 //分区号为2
First cylinder (101-391, default 101):
Using default value 101
Last cylinder or +size or +sizeM or +sizeK (101-391, default 391): +200M //分区结束位置,单位为M

确认分区建立成功:

Command (m for help): p

Disk /dev/sdb: 3221 MB, 3221225472 bytes
255 heads, 63 sectors/track, 391 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sdb1 1 100 803218+ 83 Linux
/dev/sdb2 101 125 200812+ 83 Linux

再建立一个逻辑分区:

Command (m for help): n
Command action
e extended
p primary partition (1-4)
e //选择扩展分区
Partition number (1-4): 3
First cylinder (126-391, default 126):
Using default value 126
Last cylinder or +size or +sizeM or +sizeK (126-391, default 391):
Using default value 391

确认扩展分区建立成功:

Command (m for help): p

Disk /dev/sdb: 3221 MB, 3221225472 bytes
255 heads, 63 sectors/track, 391 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sdb1 1 100 803218+ 83 Linux
/dev/sdb2 101 125 200812+ 83 Linux
/dev/sdb3 126 391 2136645 5 Extended

在扩展分区上建立两个逻辑分区:

Command (m for help): n
Command action
l logical (5 or over)
p primary partition (1-4)
l //选择逻辑分区
First cylinder (126-391, default 126):
Using default value 126
Last cylinder or +size or +sizeM or +sizeK (126-391, default 391): +400M

Command (m for help): n
Command action
l logical (5 or over)
p primary partition (1-4)
l
First cylinder (176-391, default 176):
Using default value 176
Last cylinder or +size or +sizeM or +sizeK (176-391, default 391):
Using default value 391

确认逻辑分区建立成功:

Command (m for help): p

Disk /dev/sdb: 3221 MB, 3221225472 bytes
255 heads, 63 sectors/track, 391 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sdb1 1 100 803218+ 83 Linux
/dev/sdb2 101 125 200812+ 83 Linux
/dev/sdb3 126 391 2136645 5 Extended
/dev/sdb5 126 175 401593+ 83 Linux
/dev/sdb6 176 391 1734988+ 83 Linux

Command (m for help):

从上面的结果我们可以看到,在硬盘sdb我们建立了2个主分区(sdb1,sdb2),1个扩展分区(sdb3),2个逻辑分区(sdb5,sdb6)

注意:主分区和扩展分区的磁盘号位1-4,也就是说最多有4个主分区或者扩展分区,逻辑分区开始的磁盘号为5,因此在这个实验中试没有sdb4的。

最后对分区操作进行保存:

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

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

建立好分区之后我们还需要对分区进行格式化才能在系统中使用磁盘。

在sdb1上建立ext2分区:

[root@localhost ~]# mkfs.ext2 /dev/sdb1
mke2fs 1.39 (29-May-2006)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
100576 inodes, 200804 blocks
10040 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=209715200
7 block groups
32768 blocks per group, 32768 fragments per group
14368 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840

Writing inode tables: done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 32 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.

在sdb6上建立ext3分区:

[root@localhost ~]# mkfs.ext3 /dev/sdb6
mke2fs 1.39 (29-May-2006)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
217280 inodes, 433747 blocks
21687 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=444596224
14 block groups
32768 blocks per group, 32768 fragments per group
15520 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912

Writing inode tables: done
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 32 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[root@localhost ~]#

建立两个目录/oracle/web,将新建好的两个分区挂载到系统:

[root@localhost ~]# mkdir /oracle
[root@localhost ~]# mkdir /web
[root@localhost ~]# mount /dev/sdb1 /oracle
[root@localhost ~]# mount /dev/sdb6 /web

查看分区挂载情况:

[root@localhost ~]# df -h
文件系统 容量 已用 可用 已用% 挂载点
/dev/mapper/VolGroup00-LogVol00
6.7G 2.8G 3.6G 44% /
/dev/sda1 99M 12M 82M 13% /boot
tmpfs 125M 0 125M 0% /dev/shm
/dev/sdb1 773M 808K 733M 1% /oracle
/dev/sdb6 1.7G 35M 1.6G 3% /web

如果需要每次开机自动挂载则需要修改/etc/fstab文件,加入两行配置:

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

/dev/VolGroup00/LogVol00 / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
/dev/VolGroup00/LogVol01 swap swap defaults 0 0
/dev/sdb1 /oracle ext2 defaults 0 0
/dev/sdb6 /web ext3 defaults 0 0