Linux命令之fdisk

fdisk

fdisk [选项] <disk>  改变分区表

fdisk [选项] –l <disk>  列出所有分区表

fdisk –s <partition（分区编号）>  以分区块为单位，给出指定分区的大小

　　这是一个创建和维护分区的命令，兼容DOS类型的分区表、BSD或SUN类型的磁盘列表。注意fdisk不支持2T以上的硬盘分区，此时需要使用gdisk。

相关了解：

　　磁头数（Heads）表示硬盘有几个磁头，也就是有几面盘片，一个硬盘最多有255个磁头

　　柱面数（Cylinders）表示硬盘每面盘片上有几条磁道

　　扇区数（Sectors）表示每条磁道上有几个扇区，每条磁道最多有63个扇区

(1).选项

-b <size>  指定扇区大小（512，1024，2048或4096 B）
-c  关闭DOS兼容模式
-u <size>  以扇区编号取代柱面编号来表示每个分区的起始地址，一般与-l选项联合使用
-C <number>  指定柱面编号
-H <number>  指定磁头编号
-S <number>  指定磁道扇区编号

(2).菜单操作说明：

a 设置可引导标记（活动分区/引导分区之间切换）
b 编辑BSD磁盘标签
c 设置DOS操作系统兼容标记（兼容/不兼容之间切换）
d 删除一个分区
l 显示已知的分区类型，其中82为Linux swap分区，83为Linux分区
m 显示帮助信息
n 增加一个新的分区
o 创建一个新的空白的DOS分区表
p 显示磁盘当前的分区表
q 退出fdisk程序，不保存任何修改
s 创建一个新的空白的Sun磁盘标签
t 改变一个分区的系统ID，就是改变分区类型（比如把Linux Swap分区改为Linux分区）
u 改变显示或输入单位
v 验证磁盘分区表
w 将分区表写入磁盘并退出（保存并退出）
x 额外功能（专家级）

(3).扩展

sda和hda的区别

sd代表的是SCSI，SATA接口硬盘
hd代表IDE接口的硬盘
sda和hda最后面的a都代表的是第一块硬盘
sda1和hda1则代表的是该硬盘的第一分区

(4).实例

1）.使用-l选项，列出所有分区表

/*盘/dev/sda:107.4G,107374182400字节（B）,255个磁头，63个扇区，13054柱面（磁道）
* 1单位=16065柱面（磁道）*512=8225280字节（B）
* 扇区大小（逻辑/物理）：512字节（B）/512字节（B）
*输入/输出大小（最小/最佳）：512字节（B）/512字节（B）
*磁盘标识：0x00079700
*/
Disk /dev/sda: 107.4 GB, 107374182400 bytes
255 heads, 63 sectors/track, 13054 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: 0x00079700

/*设备　　　　　启动标识　　开始位置　结束位置　　分区块的大小　　分区ID　　系统（分区类型）　
* /dev/sda1　　*　　　　　1　　　　　64　　　　 512000　　　　 83　　　　Linux
* 分区1不以柱面边界结束
* /dev/sda2　　　　　　　　64　　　　13055　　　104344576　　 8e　　　　Linux LVM
*/
   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          64      512000   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2              64       13055   104344576   8e  Linux LVM

Disk /dev/sdb: 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: 0x00000000

Disk /dev/mapper/vg_centos6-lv_root: 53.7 GB, 53687091200 bytes
255 heads, 63 sectors/track, 6527 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

Disk /dev/mapper/vg_centos6-lv_swap: 4194 MB, 4194304000 bytes
255 heads, 63 sectors/track, 509 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

Disk /dev/mapper/vg_centos6-lv_home: 49.0 GB, 48964304896 bytes
255 heads, 63 sectors/track, 5952 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

2）.使用-l和-u选项，用扇区编号取代柱面编号显示所有分区表

Disk /dev/sda: 107.4 GB, 107374182400 bytes
255 heads, 63 sectors/track, 13054 cylinders, total 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 identifier: 0x00079700

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     1026047      512000   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2         1026048   209715199   104344576   8e  Linux LVM

Disk /dev/sdb: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders, total 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 identifier: 0x00000000

Disk /dev/mapper/vg_centos6-lv_root: 53.7 GB, 53687091200 bytes
255 heads, 63 sectors/track, 6527 cylinders, total 104857600 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 identifier: 0x00000000

Disk /dev/mapper/vg_centos6-lv_swap: 4194 MB, 4194304000 bytes
255 heads, 63 sectors/track, 509 cylinders, total 8192000 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 identifier: 0x00000000

Disk /dev/mapper/vg_centos6-lv_home: 49.0 GB, 48964304896 bytes
255 heads, 63 sectors/track, 5952 cylinders, total 95633408 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 identifier: 0x00000000

3）.你们也看到了，我的/dev/sdb还没有开始使用，下面就用这个硬盘简单的演示下fdisk主要用到的操作菜单

　　1.在操作菜单下，创建一个新的分区

[root@CentOS6 桌面]# 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 0xe8517189.
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): n
Command action
   e   extended　　　　　　　　　　　　//扩展分区，创建扩展分区会占用一个主分区，并且只有创建扩展分区后才能创建逻辑分区
   p   primary partition (1-4)　　　//主分区，最多创建4个
e
Partition number (1-4): 1
First cylinder (1-2610, default 1): 　　//起始柱面，默认为1
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-2610, default 2610): 　　//终止柱面，默认为最后一个数
Using default value 2610

Command (m for help): n
Command action
   l   logical (5 or over)　　　　//逻辑分区
   p   primary partition (1-4)　 //主分区
l
First cylinder (1-2610, default 1): 1
Last cylinder, +cylinders or +size{K,M,G} (1-2610, default 2610): +10G　　//终止柱面不仅可以用柱面数表示，还可以用+[数值][单位]的格式表示

Command (m for help): n
Command action
   l   logical (5 or over)
   p   primary partition (1-4)
l
First cylinder (1307-2610, default 1307):
Using default value 1307
Last cylinder, +cylinders or +size{K,M,G} (1307-2610, default 2610):
Using default value 2610

Command (m for help): p

Disk /dev/sdb: 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: 0xe8517189

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1        2610    20964793+   5  Extended
/dev/sdb5               1        1306    10490382   83  Linux
/dev/sdb6            1307        2610    10474348+  83  Linux

Command (m for help):  w　　　　　　//写入磁盘，保存并退出，否则之前的操作都无效。如果不想写入磁盘就使用q
The partition table has been altered!

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

　　2.在操作菜单下，删除 一个分区

[root@CentOS6 桌面]# fdisk /dev/sdb

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: 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: 0xe8517189

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1        2610    20964793+   5  Extended
/dev/sdb5               1        1306    10490382   83  Linux
/dev/sdb6            1307        2610    10474348+  83  Linux

Command (m for help): d
Partition number (1-6): 6　　//这里输入的始分区编号，如果删除扩展分区，那扩展分区下的逻辑分区也会被删除

Command (m for help): p

Disk /dev/sdb: 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: 0xe8517189

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1        2610    20964793+   5  Extended
/dev/sdb5               1        1306    10490382   83  Linux

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

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

　　3.在操作菜单下，修改分区类型

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): t
Partition number (1-5): 5　　//操作哪一个分区
Hex code (type L to list codes): L　　//这里会提示你使用L查看类型列表

 0  Empty           24  NEC DOS         81  Minix / old Lin bf  Solaris
 1  FAT12           39  Plan 9          82  Linux swap / So c1  DRDOS/sec (FAT-
 2  XENIX root      3c  PartitionMagic  83  Linux           c4  DRDOS/sec (FAT-
 3  XENIX usr       40  Venix 80286     84  OS/2 hidden C:  c6  DRDOS/sec (FAT-
 4  FAT16 <32M      41  PPC PReP Boot   85  Linux extended  c7  Syrinx
 5  Extended        42  SFS             86  NTFS volume set da  Non-FS data
 6  FAT16           4d  QNX4.x          87  NTFS volume set db  CP/M / CTOS / .
 7  HPFS/NTFS       4e  QNX4.x 2nd part 88  Linux plaintext de  Dell Utility
 8  AIX             4f  QNX4.x 3rd part 8e  Linux LVM       df  BootIt
 9  AIX bootable    50  OnTrack DM      93  Amoeba          e1  DOS access
 a  OS/2 Boot Manag 51  OnTrack DM6 Aux 94  Amoeba BBT      e3  DOS R/O
 b  W95 FAT32       52  CP/M            9f  BSD/OS          e4  SpeedStor
 c  W95 FAT32 (LBA) 53  OnTrack DM6 Aux a0  IBM Thinkpad hi eb  BeOS fs
 e  W95 FAT16 (LBA) 54  OnTrackDM6      a5  FreeBSD         ee  GPT
 f  W95 Ext'd (LBA) 55  EZ-Drive        a6  OpenBSD         ef  EFI (FAT-12/16/
10  OPUS            56  Golden Bow      a7  NeXTSTEP        f0  Linux/PA-RISC b
11  Hidden FAT12    5c  Priam Edisk     a8  Darwin UFS      f1  SpeedStor
12  Compaq diagnost 61  SpeedStor       a9  NetBSD          f4  SpeedStor
14  Hidden FAT16 <3 63  GNU HURD or Sys ab  Darwin boot     f2  DOS secondary
16  Hidden FAT16    64  Novell Netware  af  HFS / HFS+      fb  VMware VMFS
17  Hidden HPFS/NTF 65  Novell Netware  b7  BSDI fs         fc  VMware VMKCORE
18  AST SmartSleep  70  DiskSecure Mult b8  BSDI swap       fd  Linux raid auto
1b  Hidden W95 FAT3 75  PC/IX           bb  Boot Wizard hid fe  LANstep
1c  Hidden W95 FAT3 80  Old Minix       be  Solaris boot    ff  BBT
1e  Hidden W95 FAT1
Hex code (type L to list codes): b
Changed system type of partition 5 to b (W95 FAT32)

Command (m for help): p　　//可以看到由原来的Linux改成了W95 FAT32

Disk /dev/sdb: 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: 0xe8517189

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1        2610    20964793+   5  Extended
/dev/sdb5               1        1306    10490382    b  W95 FAT32

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

Calling ioctl() to re-read partition table.

WARNING: If you have created or modified any DOS 6.x
partitions, please see the fdisk manual page for additional
information.
Syncing disks.

4）.对正在使用的磁盘，再次进行分区时会出现以下提示

WARNING: Re-reading the partition table failed with error 16: 设备或资源忙.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)

　　注意此时分区并不会立刻生效，可以重启系统，也可以使用提示的命令partprobe或kpartx。

　　下面展示完整情况内容

[root@xuexi ~]# fdisk /dev/sdb
欢迎使用 fdisk (util-linux 2.23.2)。

更改将停留在内存中，直到您决定将更改写入磁盘。
使用写入命令前请三思。

命令(输入 m 获取帮助)：n　　//新建分区
Partition type:
   p   primary (1 primary, 0 extended, 3 free)
   e   extended
Select (default p): p　　//创建主分区
分区号 (2-4，默认 2)：
起始 扇区 (2099200-4194303，默认为 2099200)：
将使用默认值 2099200
Last 扇区, +扇区 or +size{K,M,G} (2099200-4194303，默认为 4194303)：
将使用默认值 4194303
分区 2 已设置为 Linux 类型，大小设为 1023 MiB

命令(输入 m 获取帮助)：w　　//写入磁盘
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: 设备或资源忙.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
正在同步磁盘。
[root@xuexi ~]# ls /dev/sdb*
/dev/sdb  /dev/sdb1
[root@xuexi ~]# partprobe /dev/sdb　　//通知操作系统分区表已更改
[root@xuexi ~]# ls /dev/sdb*
/dev/sdb  /dev/sdb1  /dev/sdb2

　　注意：能reboot重启最好重启，不行再使用命令更新

　　注意：其实partprobe是更新分区表，但kpartx其实是更新分区映射（涉及到了镜像文件，例如.img文件），不过还有partx可以用来更新分区表（-a选项新增，-d选项删除，-u选项更新（好像不能在删除时使用））。