Linux查看已经分好的区
[root@linuxidc ~]# fdisk -l /dev/sda 
  
Disk /dev/sda: 21.5 GB, 21474836480 bytes 
255 heads, 63 sectors/track, 2610 cylinders 
Units = cylinders of 16065 * 512 = 8225280bytes 
Sector size (logical/physical): 512 bytes /512 bytes 
I/O size (minimum/optimal): 512 bytes / 512bytes 
Disk identifier: 0x7d57cb1f 
  
  Device Boot      Start        End      Blocks  Id  System 
/dev/sda1              1        2610  20964793+  5  Extended 
/dev/sda5              1        128    1028097  83  Linux 
/dev/sda6            129        256    1028128+  83  Linux 
/dev/sda7            257        384    1028128+  83  Linux

格式化新分区的时候，报错，提示下面的错误，没有这个文件或目录。

Could not stat /dev/sda7 --- No such fileor directory
The device apparently does not exist; didyou specify it correctly?

[root@linuxidc ~]# mke2fs -t ext4 /dev/sda7 
mke2fs 1.41.12 (17-May-2010) 
Could not stat /dev/sda7 --- No such fileor directory 
  
The device apparently does not exist; didyou specify it correctly?

解决方法：执行partprobe 命令
partprobe包含在parted的rpm软件包中。
partprobe可以修改kernel中分区表，使kernel重新读取分区表。 
因此，使用该命令就可以创建分区并且在不重新启动机器的情况下系统能够识别这些分区。
 
查看是否安装过该命令：
[root@linuxidc~]# rpm -q parted 
packageparted is not installed

提示没有安装过，则需要安装parted
安装命令：#yum install parted #前提是保证你的虚拟机可以上网，要从网络下载安装包
[root@linuxidc~]# yum install parted

Loadedplugins: fastestmirror
1234567 Loadingmirror speeds from cached hostfile 
 * base: mirrors.skyshe.cn 
 * extras: mirrors.skyshe.cn 
 * updates: mirrors.skyshe.cn 
base                                                | 3.7 kB    00:00      
extras                                                |3.3 kB    00:00      
updates                                              | 3.4 kB    00:00

Settingup Install Process 
ResolvingDependencies 
-->Running transaction check 
--->Package parted.i686 0:2.1-25.el6 will be installed 
-->Finished Dependency Resolution 
  
DependenciesResolved 
  
============================================================================= 
 Package          Arch          Version                Repository      Size 
============================================================================= 
Installing: 
 parted          i686          2.1-25.el6            base          595 k 
  
TransactionSummary 
============================================================================= 
Install      1 Package(s) 
  
Totaldownload size: 595 k 
Installedsize: 2.1 M 
Isthis ok [y/N]: y 
DownloadingPackages: 
parted-2.1-25.el6.i686.rpm                            | 595 kB    00:16      
Runningrpm_check_debug 
RunningTransaction Test 
TransactionTest Succeeded 
RunningTransaction 
  Installing : parted-2.1-25.el6.i686                                    1/1 
  Verifying : parted-2.1-25.el6.i686                                  1/1 
  
Installed: 
  parted.i686 0:2.1-25.el6                                                  
  
Complete!

安装完成后，再进行查询一次，已经安装成功。
[root@linuxidc~]# rpm -q parted 
parted-2.1-25.el6.i686

执行一下该命令：
[root@linuxidc~]# partprobe 
Warning:WARNING: the kernel failed to re-read the partition table on /dev/sda (Deviceor resource busy).  As a result, it maynot reflect all of your changes until after reboot. 
Warning:WARNING: the kernel failed to re-read the partition table on /dev/sdb (Deviceor resource busy).  As a result, it maynot reflect all of your changes until after reboot. 
Warning:Unable to open /dev/sr0 read-write (Read-only file system).  /dev/sr0 has been opened read-only. 
Warning:Unable to open /dev/sr0 read-write (Read-only file system).  /dev/sr0 has been opened read-only. 
Error:Invalid partition table - recursive partition on /dev/sr0.

然后执行格式化，就OK了，如果还提示出错，重启之后再执行格式化就可以了。
[root@linuxidc~]# mkfs -t ext4 /dev/sda7 
mke2fs1.41.12 (17-May-2010) 
Filesystemlabel= 
OStype: Linux 
Blocksize=4096 (log=2) 
Fragmentsize=4096 (log=2) 
Stride=0blocks, Stripe width=0 blocks 
64384inodes, 257032 blocks 
12851blocks (5.00%) reserved for the super user 
Firstdata block=0 
Maximumfilesystem blocks=264241152 
8block groups
32768blocks per group, 32768 fragments per group 
8048inodes per group 
Superblockbackups stored on blocks:  
    32768, 98304, 163840, 229376 
  
Writinginode tables: done                          
Creatingjournal (4096 blocks): done
Writingsuperblocks and filesystem accounting information: done
  
Thisfilesystem will be automatically checked every 35 mounts or 
180days, whichever comes first.  Use tune2fs-c or -i to override.