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））。
