何为磁盘分区，为什么要分区？
计算机中存放信息的主要的存储设备就是硬盘，但是硬盘不能直接使用，必须对硬盘进行分割，分割成的一块一块的硬盘区域就是磁盘分区。在传统的磁盘管理中，将一个硬盘分为两大类分区：主分区和扩展分区。主分区是能够安装操作系统，能够进行计算机启动的分区，这样的分区可以直接格式化，然后安装系统，直接存放文件。
MBR分区结构
在一个MBR分区表类型的硬盘中最多只能存在4个主分区。如果一个硬盘上需要超过4个以上的磁盘分块的话，那么就需要使用扩展分区了。如果使用扩展分区，那么一个物理硬盘上最多只能3个主分区和1个扩展分区。扩展分区不能直接使用，它必须经过第二次分割成为一个一个的逻辑分区，然后才可以使用。一个扩展分区中的逻辑分区可以任意多个。
1、Linux磁盘分区查看
[root@centos6 ~]# fdisk -l Disk /dev/sda: 214.7 GB, 214748364800 bytes 255 heads, 63 sectors/track, 26108 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: 0x00007b7d 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 12774 102400000 83 Linux /dev/sda3 12774 14049 10240000 83 Linux /dev/sda4 14049 26109 96869376 5 Extended /dev/sda5 14049 14310 2097152 82 Linux swap / Solaris
/dev/sda: 214.7 GB #该sda硬盘磁盘容量为 214.7GB 214748364800 bytes：总共 214748364800 字节 255 heads：255个磁头 63 sectors/track：一个盘面总共63个扇区 26108 cylinders：26108个柱面 Units = cylinders of 16065 * 512 = 8225280 bytes：每个柱面（cylinders ）总共有 16065个扇区，每个扇区总共 512字节，所以每个柱面总共为 16065*512 =8225280 bytes（字节） Sector size (logical/physical): 512 bytes / 512 bytes：每个扇区的逻辑和物理容量大小都为 512 bytes（字节） I/O size (minimum/optimal): 512 bytes / 512 bytes：I/O的容量最小和最佳值都为 512 bytes（字节） Disk identifier: 0x00007b7d：磁盘标识符为 0x00007b7d
Device：设备名称 Boot：是否可引导 Start：起始柱面 End：结束柱面 Blocks：包含的磁盘块数 Id：分区标识 System：应用在那个系统在上常用的分区标识 /dev/sda1：分区名称 *：可引导设备 1：从第1个柱面开始 26：在第26个柱面结束 204800：磁盘块数为204800 83：分区ID标识为83 Linux：应用在linux系统之上 /dev/sda2：分区名称 26：从第26个柱面开始 12774：在第12774个柱面结束 102400000：磁盘块数为102400000 83：分区ID标识为83 Linux：应用在linux系统之上 /dev/sda3：分区名称 12774：从第12774柱面开始 14049：在第14049个柱面结束 10240000：磁盘块数为10240000 83：分区ID标识为83 Linux：应用在linux系统之上 /dev/sda4：分区名称 14049: 从第14049个柱面开始 26109：在第26109个柱面结束 96869376：磁盘块数为96869376 5：分区ID标识为5 Extended：应用在linux系统扩展分区之上 /dev/sda5：分区名称 14049：从第14049个柱面开始 14310：在第14310个柱面结束 2097152：磁盘块数为2097152 82：分区ID标识为82 Linux swap / Solaris：应用在linux系统swap之上
2、Linux磁盘分区
fdisk 命令
简介： fdisk - Partition table manipulator for Linux
格式： fdisk [-uc] [-b sectorsize] [-C cyls] [-H heads] [-S sects] device fdisk -l [-u] [device...] fdisk -s partition... fdisk -v fdisk -h
Command action a toggle a bootable flag #设置一个标识，说明这个分区是可启动的 b edit bsd disklabel #编辑BSD Linux系统用的磁盘标签 c toggle the dos compatibility flag #设置DOS兼容标识 d delete a partition #删除分区 l list known partition types #显示可用的分区类型 m print this menu #显示命令先选项帮助手册 n add a new partition #添加一个新分区 o create a new empty DOS partition table #创建DOS分区表 p print the partition table #显示当前分区表 q quit without saving changes #退出，不保存更改 s create a new empty Sun disklabel #为Sun Linux系统创建一个新磁盘标签 t change a partition's system id #修改分区的系统ID u change display/entry units #改变使用的存储单元 v verify the partition table #验证分区表 w write table to disk and exit #将分区表写入磁盘 x extra functionality (experts only) #高级功能
实例1：
[root@centos6 ~]# fdisk /dev/sda #对sda这块硬盘进行分区管理
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 #查看当前分区情况
Disk /dev/sda: 214.7 GB, 214748364800 bytes
255 heads, 63 sectors/track, 26108 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: 0x00007b7d
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 12774 102400000 83 Linux
/dev/sda3 12774 14049 10240000 83 Linux
/dev/sda4 14049 26109 96869376 5 Extended
/dev/sda5 14049 14310 2097152 82 Linux swap / Solaris
Command (m for help): n #创建一个新分区
First cylinder (14310-26109, default 14310): #默认以柱面进行分区，默认柱面开始值为14310，直接回车就是选择默认值
Using default value 14310
Last cylinder, +cylinders or +size{K,M,G} (14310-26109, default 26109): 14500 #填写结束柱面值14500
Command (m for help): p #查看以分好的区
Disk /dev/sda: 214.7 GB, 214748364800 bytes
255 heads, 63 sectors/track, 26108 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: 0x00007b7d
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 12774 102400000 83 Linux
/dev/sda3 12774 14049 10240000 83 Linux
/dev/sda4 14049 26109 96869376 5 Extended
/dev/sda5 14049 14310 2097152 82 Linux swap / Solaris
/dev/sda6 14310 14500 1526194+ 83 Linux
Command (m for help): w #确认不再做任何操作，直接保存退出
The partition table has been altered!
Calling ioctl() to re-read partition table.
WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
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)
Syncing disks.
[root@centos6 ~]# fdisk -l #查看分区情况（真实情况）
Disk /dev/sda: 214.7 GB, 214748364800 bytes
255 heads, 63 sectors/track, 26108 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: 0x00007b7d
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 12774 102400000 83 Linux
/dev/sda3 12774 14049 10240000 83 Linux
/dev/sda4 14049 26109 96869376 5 Extended
/dev/sda5 14049 14310 2097152 82 Linux swap / Solaris
/dev/sda6 14310 14500 1526194+ 83 Linux
[root@centos6 ~]# cat /proc/partitions #查看是否已写入内核中，显示并唯有逻辑分区/dev/sda6
major minor #blocks name
8 0 209715200 sda
8 1 204800 sda1
8 2 102400000 sda2
8 3 10240000 sda3
8 4 1 sda4
8 5 2097152 sda5
[root@centos6 ~]# partx -a /dev/sda #可用此方法让内核扫描分区情况
BLKPG: Device or resource busy
error adding partition 1
BLKPG: Device or resource busy
error adding partition 2
BLKPG: Device or resource busy
error adding partition 3
BLKPG: Device or resource busy
error adding partition 4
BLKPG: Device or resource busy
error adding partition 5
[root@centos6 ~]# partx -a /dev/sda #如果第一次扫描未有显示，可再次执行该命令
BLKPG: Device or resource busy
error adding partition 1
BLKPG: Device or resource busy
error adding partition 2
BLKPG: Device or resource busy
error adding partition 3
BLKPG: Device or resource busy
error adding partition 4
BLKPG: Device or resource busy
error adding partition 5
BLKPG: Device or resource busy
error adding partition 6
[root@centos6 ~]# cat /proc/partitions #查看内核是否已识别
major minor #blocks name
8 0 209715200 sda
8 1 204800 sda1
8 2 102400000 sda2
8 3 10240000 sda3
8 4 1 sda4
8 5 2097152 sda5
8 6 1526194 sda6
[root@centos6 ~]# ls /dev/sda* #也可以用此类方法查看
/dev/sda /dev/sda1 /dev/sda2 /dev/sda3 /dev/sda4 /dev/sda5 /dev/sda6
[root@centos6 ~]# lsblk #也可以用这种方法查看
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sr0 11:0 1 1024M 0 rom
sda 8:0 0 200G 0 disk
├─sda1 8:1 0 200M 0 part /boot
├─sda2 8:2 0 97.7G 0 part /
├─sda3 8:3 0 9.8G 0 part /testdir
├─sda4 8:4 0 1K 0 part
├─sda5 8:5 0 2G 0 part [SWAP]
└─sda6 8:6 0 1.5G 0 part
[root@centos6 ~]#
实例2： [root@centos6 ~]# partx -d -n 6 /dev/sda #不用fdisk命令，直接用partx命令删除分区 [root@centos6 ~]# cat /proc/partitions major minor #blocks name 8 0 209715200 sda 8 1 204800 sda1 8 2 102400000 sda2 8 3 10240000 sda3 8 4 1 sda4 8 5 2097152 sda5
实例3:
[root@centos6 ~]# 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): n #创建一个新分区
First cylinder (14310-26109, default 14310):
Using default value 14310 #默认起始柱面
Last cylinder, +cylinders or +size{K,M,G} (14310-26109, default 26109): 15000 #设置结束柱面为15000
Command (m for help): t #设置分区类型
Partition number (1-6): 6
Hex code (type L to list codes): 82 #设置分区类型为82，也就是swap分区
Changed system type of partition 6 to 82 (Linux swap / Solaris)
Command (m for help): p #查看分区情况
Disk /dev/sda: 214.7 GB, 214748364800 bytes
255 heads, 63 sectors/track, 26108 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: 0x00007b7d
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 12774 102400000 83 Linux
/dev/sda3 12774 14049 10240000 83 Linux
/dev/sda4 14049 26109 96869376 5 Extended
/dev/sda5 14049 14310 2097152 82 Linux swap / Solaris
/dev/sda6 14310 15000 5542444+ 82 Linux swap / Solaris
Command (m for help): w #保持退出
The partition table has been altered!
Calling ioctl() to re-read partition table.
WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
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)
Syncing disks.
[root@centos6 ~]# partx -a /dev/sda #让内核扫描分区
BLKPG: Device or resource busy
error adding partition 1
BLKPG: Device or resource busy
error adding partition 2
BLKPG: Device or resource busy
error adding partition 3
BLKPG: Device or resource busy
error adding partition 4
BLKPG: Device or resource busy
error adding partition 5
[root@centos6 ~]# partx -a /dev/sda
BLKPG: Device or resource busy
error adding partition 1
BLKPG: Device or resource busy
error adding partition 2
BLKPG: Device or resource busy
error adding partition 3
BLKPG: Device or resource busy
error adding partition 4
BLKPG: Device or resource busy
error adding partition 5
BLKPG: Device or resource busy
error adding partition 6
[root@centos6 ~]# lsblk #查看内核已经识别分好的分区
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sr0 11:0 1 1024M 0 rom
sda 8:0 0 200G 0 disk
├─sda1 8:1 0 200M 0 part /boot
├─sda2 8:2 0 97.7G 0 part /
├─sda3 8:3 0 9.8G 0 part /testdir
├─sda4 8:4 0 1K 0 part
├─sda5 8:5 0 2G 0 part [SWAP]
└─sda6 8:6 0 5.3G 0 part
[root@centos6 ~]# fdisk -l /dev/sda #再次查看分区情况
Disk /dev/sda: 214.7 GB, 214748364800 bytes
255 heads, 63 sectors/track, 26108 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: 0x00007b7d
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 12774 102400000 83 Linux
/dev/sda3 12774 14049 10240000 83 Linux
/dev/sda4 14049 26109 96869376 5 Extended
/dev/sda5 14049 14310 2097152 82 Linux swap / Solaris
/dev/sda6 14310 15000 5542444+ 82 Linux swap / Solaris
[root@centos6 ~]#
原创文章，作者：Aleen，如若转载，请注明出处：http://www.178linux.com/40689
