fdisk 命令

fdisk 命令

语法 fdisk [-l] [设备名称]
-l 后边不跟设备名会直接列出系统中所有的磁盘设备以及分区表，加上设备名会列出该设备的分区表。
[root@localhost ~]# fdisk -l
Disk /dev/sda: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
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 identifier: 0x000eb8f3
Device Boot Start End Blocks Id System
/dev/sda1 * 1 26 204800 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 26 287 2097152 82 Linux swap / Solaris
Partition 2 does not end on cylinder boundary.
/dev/sda3 287 2611 18668544 83 Linux
Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
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 identifier: 0x00000000
对比一下：
[root@localhost ~]# fdisk -l /dev/sda
Disk /dev/sda: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
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 identifier: 0x000eb8f3
Device Boot Start End Blocks Id System
/dev/sda1 * 1 26 204800 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 26 287 2097152 82 Linux swap / Solaris
Partition 2 does not end on cylinder boundary.
/dev/sda3 287 2611 18668544 83 Linux
可以看到一块儿未被分区的磁盘 /dev/sdb 的信息。

fdisk 如果不加 -l 则进入另一个模式，在该模式下，可以对磁盘进行分区操作。
[root@localhost ~]# fdisk /dev/sda
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): m //输入 m 会列出常用的命令
Command action
a toggle a bootable flag
b edit bsd disklabel
c toggle the dos compatibility flag
d delete a partition
l list known partition types
m print this menu
n add a new partition
o create a new empty DOS partition table
p print the partition table
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
x extra functionality (experts only)
p 打印当前磁盘的分区情况：
Command (m for help): p
Disk /dev/sda: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
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 identifier: 0x000eb8f3
Device Boot Start End Blocks Id System
/dev/sda1 * 1 26 204800 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 26 287 2097152 82 Linux swap / Solaris
Partition 2 does not end on cylinder boundary.
/dev/sda3 287 2611 18668544 83 Linux
n 建立一个新的分区
w 保存操作
q 退出
d 删除一个分区

下面把刚刚显示的未分区磁盘 /dev/sdb 进行分区
[root@localhost ~]# fdisk /dev/sdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x4cb6a167.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): p
Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
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 identifier: 0x4cb6a167
Device Boot Start End Blocks Id System
Command (m for help):
可以看到目前/dev/sdb 没有任何分区，下面建立第一个分区：
Command (m for help): n //使用 n 命令新建分区
Command action //它会提示是要 e（扩展分区）还是要 p （主分区）。这里选择 p
e extended
p primary partition (1-4)
p
Partition number (1-4): 1 //提示分区数，这里选择1
First cylinder (1-1305, default 1): 1 //提示第一个柱面从哪里开始，默认是1，直接回车也会按1处理。
Last cylinder, +cylinders or +size{K,M,G} (1-1305, default 1305): +1024M //提示输入最后一个柱面的数值，使用另一种方法：+容量 单位
Command (m for help): p //再次查看会发现多出了一个分区
Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
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 identifier: 0x4cb6a167
Device Boot Start End Blocks Id System
/dev/sdb1 1 132 1060258+ 83 Linux
Command (m for help):
继续上面的操作，一直创建主分区到4，然后再一次创建分区时会提示：
Command (m for help): n
You must delete some partition and add an extended partition first
这是因为在linux系统中最多只能创建4个主分区。如果想要多创建几个分区需要有一个扩展分区，例如把第四个分区创建成扩展分区
Command (m for help): n
Command action
e extended
p primary partition (1-4)
e
Selected partition 4
First cylinder (397-1305, default 397):
Using default value 397
Last cylinder, +cylinders or +size{K,M,G} (397-1305, default 1305): //第四个扩展分区需要把剩余的磁盘空间全部占用
Using default value 1305
Command (m for help): p
Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
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 identifier: 0x4cb6a167
Device Boot Start End Blocks Id System
/dev/sdb1 1 132 1060258+ 83 Linux
/dev/sdb2 133 264 1060290 83 Linux
/dev/sdb3 265 396 1060290 83 Linux
/dev/sdb4 397 1305 7301542+ 5 Extended //扩展分区，在最后一列显示为 Extended
继续创建：
Command (m for help): n
First cylinder (397-1305, default 397): //这时候不再选择主分区还是扩展分区了，而是直接定义大小
Using default value 397
Last cylinder, +cylinders or +size{K,M,G} (397-1305, default 1305): +1024M
Command (m for help): p
Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
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 identifier: 0x4cb6a167
Device Boot Start End Blocks Id System
/dev/sdb1 1 132 1060258+ 83 Linux
/dev/sdb2 133 264 1060290 83 Linux
/dev/sdb3 265 396 1060290 83 Linux
/dev/sdb4 397 1305 7301542+ 5 Extended
/dev/sdb5 397 528 1060258+ 83 Linux
当分完三个主分区后，第四个扩展分区要占用全部剩余空间的原因是：分完扩展分区后，再划分新的分区是在已经划分的扩展分区上去划分的。其中/dev/sdb4为扩展分区，它是不可以被格式化的，就相当于一个空壳子，能使用的为/dev/sdb5，这个分区叫做逻辑分区，是/dev/sdb4的子分区。

删除某分区： d 命令
Command (m for help): d
Partition number (1-5): 1
Command (m for help): p
Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
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 identifier: 0x4cb6a167
Device Boot Start End Blocks Id System
/dev/sdb2 133 264 1060290 83 Linux
/dev/sdb3 265 396 1060290 83 Linux
/dev/sdb4 397 1305 7301542+ 5 Extended
/dev/sdb5 397 528 1060258+ 83 Linux
Command (m for help): d
Partition number (1-5): 5
Command (m for help): p
Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
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 identifier: 0x4cb6a167
Device Boot Start End Blocks Id System
/dev/sdb2 133 264 1060290 83 Linux
/dev/sdb3 265 396 1060290 83 Linux
/dev/sdb4 397 1305 7301542+ 5 Extended
Command (m for help): n
Command action
l logical (5 or over)
p primary partition (1-4)
l
First cylinder (397-1305, default 397):
Using default value 397
Last cylinder, +cylinders or +size{K,M,G} (397-1305, default 1305): +1024M
Command (m for help): p
Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
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 identifier: 0x4cb6a167
Device Boot Start End Blocks Id System
/dev/sdb2 133 264 1060290 83 Linux
/dev/sdb3 265 396 1060290 83 Linux
/dev/sdb4 397 1305 7301542+ 5 Extended
/dev/sdb5 397 528 1060258+ 83 Linux
Command (m for help): d
Partition number (1-5): 4
Command (m for help): p
Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
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 identifier: 0x4cb6a167
Device Boot Start End Blocks Id System
/dev/sdb2 133 264 1060290 83 Linux
/dev/sdb3 265 396 1060290 83 Linux
输入d会提示要删除那个分区，可以选择1-5，其中1-3为主分区。4是扩展分区，5是逻辑分区。如果输入5，则直接把逻辑分区sdb5删除掉，如果输入4，则会把整个扩展分区sdb4干掉，也包含扩展分区里面的逻辑分区。在刚才的界面中直接Ctrl+C退出来，这样刚刚的分区全部都取消了。

重新做分区：
[root@localhost ~]# fdisk /dev/sdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0xb2b18b55.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): p
Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
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 identifier: 0xb2b18b55
Device Boot Start End Blocks Id System
Command (m for help): n
Command action
e extended
p primary partition (1-4)
e
Partition number (1-4): 1
First cylinder (1-1305, default 1):
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-1305, default 1305):
Using default value 1305
Command (m for help): p
Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
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 identifier: 0xb2b18b55
Device Boot Start End Blocks Id System
/dev/sdb1 1 1305 10482381 5 Extended
Command (m for help): n
Command action
l logical (5 or over)
p primary partition (1-4)
l
First cylinder (1-1305, default 1):
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-1305, default 1305): +1024M
Command (m for help): p
Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
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 identifier: 0xb2b18b55
Device Boot Start End Blocks Id System
/dev/sdb1 1 1305 10482381 5 Extended
/dev/sdb5 1 132 1060227 83 Linux
Command (m for help): n
Command action
l logical (5 or over)
p primary partition (1-4)
l
First cylinder (133-1305, default 133):
Using default value 133
Last cylinder, +cylinders or +size{K,M,G} (133-1305, default 1305): +1024M
Command (m for help): p
Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
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 identifier: 0xb2b18b55
Device Boot Start End Blocks Id System
/dev/sdb1 1 1305 10482381 5 Extended
/dev/sdb5 1 132 1060227 83 Linux
/dev/sdb6 133 264 1060258+ 83 Linux
Command (m for help): w // w 命令保存配置
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
查看分区情况
[root@localhost ~]# fdisk -l /dev/sdb
Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
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 identifier: 0xb2b18b55
Device Boot Start End Blocks Id System
/dev/sdb1 1 1305 10482381 5 Extended
/dev/sdb5 1 132 1060227 83 Linux
/dev/sdb6 133 264 1060258+ 83 Linux