【Linux】磁盘分区

我们在Linux操作过程中，可能会遇到磁盘分区的问题。这篇文章是对/dev/sdb 这块磁盘进行分区。
linux分区不同于windows，linux下硬盘设备名为（IDE硬盘为hdx（x为从a—d）因为IDE硬盘最多四个，SCSI，SATA，USB硬盘为sdx（x为a—z）），硬盘主分区最多为4个，不用说大家也知道…..所以主分区从sdb1开始到sdb4，逻辑分区从sdb5开始，（逻辑分区永远从sdb5开始…）
主分区（最多创建4个）：第一个分区主要存放磁盘的启动信息。
扩展分区（Linux中最多创建1个）：扩展分区属于逻辑架构，不能再创建文件系统，只能在下面创建逻辑分区。
逻辑分区：在扩展分区下面创建，不同的操作系统对逻辑分区个数限制也不同。
分区步骤：
1.fdisk 分区;
2.mkfs 格式化分区;
3.创建挂载点;
4.挂载磁盘或者编辑/etc/fstab文件设置开机自动挂载

1.查看当前操作系统的所有磁盘

[root@lgr ~]# fdisk -l

Disk /dev/sda: 42.9 GB, 42949672960 bytes
255 heads, 63 sectors/track, 5221 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          13      104391   83  Linux
/dev/sda2              14         535     4192965   82  Linux swap / Solaris
/dev/sda3             536        5221    37640295   83  Linux

Disk /dev/sdb: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/sdb doesn't contain a valid partition table

2.fdisk命令把sdb分成1个主分区，一个扩展分区

[root@lgr ~]# fdisk /dev/sdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.

The number of cylinders for this disk is set to 1305.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
   (e.g., DOS FDISK, OS/2 FDISK)
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-1305, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-1305, default 1305): +5G

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
e
Partition number (1-4): 2
First cylinder (610-1305, default 610):
Using default value 610
Last cylinder or +size or +sizeM or +sizeK (610-1305, default 1305):
Using default value 1305

Command (m for help): n
Command action
   l   logical (5 or over)
   p   primary partition (1-4)
l
First cylinder (610-1305, default 610):
Using default value 610
Last cylinder or +size or +sizeM or +sizeK (610-1305, default 1305): +3G

Command (m for help):
Command (m for help): n
Command action
   l   logical (5 or over)
   p   primary partition (1-4)
l
First cylinder (976-1305, default 976):
Using default value 976
Last cylinder or +size or +sizeM or +sizeK (976-1305, default 1305): +2G

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

Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1         609     4891761   83  Linux
/dev/sdb2             610        1305     5590620    5  Extended
/dev/sdb5             610         975     2939863+  83  Linux
/dev/sdb6             976        1219     1959898+  83  Linux

Command (m for help): w
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.
Syncing disks.

3.mkfs命令对分区进行格式化

[root@lgr ~]# mkfs.ext3 /dev/sdb1
mke2fs 1.39 (29-May-2006)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
611648 inodes, 1222940 blocks
61147 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=1254096896
38 block groups
32768 blocks per group, 32768 fragments per group
16096 inodes per group
Superblock backups stored on blocks:
    32768, 98304, 163840, 229376, 294912, 819200, 884736

Writing inode tables: done                            
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 30 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.
[root@lgr ~]#
[root@lgr ~]# mkfs.ext3 /dev/sdb5
mke2fs 1.39 (29-May-2006)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
368000 inodes, 734965 blocks
36748 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=754974720
23 block groups
32768 blocks per group, 32768 fragments per group
16000 inodes per group
Superblock backups stored on blocks:
    32768, 98304, 163840, 229376, 294912

Writing inode tables: done                            
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 37 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.
[root@lgr ~]# 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)
245280 inodes, 489974 blocks
24498 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=503316480
15 block groups
32768 blocks per group, 32768 fragments per group
16352 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 30 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

4.创建挂载点

[root@lgr ~]# mkdir /dsk1 /dsk5 /dsk6

5.mount命令做一次临时挂载，编辑/etc/fstab 可以设置开机自动挂载。

①临时挂载
mount /dev/sdb1 /dsk1
mount /dev/sdb5 /dsk5
mount /dev/sdb6 /dsk6

②编辑文件设置自动挂载
[root@lgr ~]# vi /etc/fstab
追加如下信息
/dev/sdb1               /dsk1                   ext3    defaults        0 0
/dev/sdb5               /dsk5                   ext3    defaults        0 0
/dev/sdb6               /dsk6                   ext3    defaults        0 0
说明：第一行：磁盘目录;第二行：挂载点;第三行：文件系统格式;第四行：启动磁盘方式;第五行：开机是否检测（0 不检测，1 检测);第六行：出错是否转储（0，不转储，1 转储）

6.重启系统，fdisk-l /dev/sdb 查看分区情况。