安装centos6.3使用自动推荐分区，发现一个问题/home 分区过大，超过了1.1T。

[root:coshina ~]# df -h 
    文件系统              容量  已用  可用 已用%% 挂载点 
    /dev/mapper/VolGroup-lv_root 
                           50G  2.9G   44G   7% / 
    tmpfs                 5.9G  100K  5.9G   1% /dev/shm 
    /dev/sda1             485M   37M  423M   8% /boot 
    /dev/mapper/VolGroup-lv_home 
                          1.1T  200M  988G   1% /home

目标：/home分20G，剩下添加给/目录下。

1.查看分区模式

[root:coshina ~]# df -h 
文件系统              容量  已用  可用 已用%% 挂载点 
/dev/mapper/VolGroup-lv_root 
                       50G  2.9G   44G   7% / 
tmpfs                 5.9G  100K  5.9G   1% /dev/shm 
/dev/sda1             485M   37M  423M   8% /boot 
/dev/mapper/VolGroup-lv_home 
                      1.1T  200M  988G   1% /home

2.卸载挂载分区

[root:coshina ~]# umount /home

3.检查VolGroup-lv_home文件的错误性，-f 即使文件系统没有错误迹象，仍强制地检查正确性。

[root:coshina ~]# e2fsck -f /dev/mapper/VolGroup-lv_home 
e2fsck 1.41.12 (17-May-2010) 
第一步: 检查inode,块,和大小 
第二步: 检查目录结构 
第3步: 检查目录连接性 
Pass 4: Checking reference counts 
第5步: 检查簇概要信息 
/dev/mapper/VolGroup-lv_home: 27/69304320 files (0.0% non-contiguous),4400705/277215232 blocks

4.调整/home为20G，

[root:coshina ~]# resize2fs -p /dev/mapper/VolGroup-lv_home 20G
 resize2fs 1.41.12 (17-May-2010) 
 Resizing the filesystem on /dev/mapper/VolGroup-lv_home to 5242880 (4k) blocks. 
 Begin pass 2 (max = 32784) 
 正在重定位块            XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 
 Begin pass 3 (max = 8460) 
 正在扫描inode表          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 
 Begin pass 4 (max = 15) 
 正在更新inode引用       XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 
 The filesystem on /dev/mapper/VolGroup-lv_home is now 5242880 blocks long.

5.重新挂载并查看

[root:coshina ~]# mount /home 
[root:coshina ~]# df -h 
文件系统              容量  已用  可用 已用%% 挂载点 
/dev/mapper/VolGroup-lv_root 
                       50G  2.9G   44G   7% / 
tmpfs                 5.9G  100K  5.9G   1% /dev/shm 
/dev/sda1             485M   37M  423M   8% /boot 
/dev/mapper/VolGroup-lv_home 
                       20G  172M   19G   1% /home

6.划分20G外面的剩余空间。使用lvreduce指令用于减少LVM逻辑卷占用的空间大小。可能会删除逻辑卷上已有的数据，所以在操作前必须进行确认。记得输入 “y”

[root:coshina ~]# lvreduce -L 20G /dev/mapper/VolGroup-lv_home 
  WARNING: Reducing active and open logical volume to 20.00 GiB 
  THIS MAY DESTROY YOUR DATA (filesystem etc.) 
Do you really want to reduce lv_home? [y/n]: y 
  Reducing logical volume lv_home to 20.00 GiB 
  Logical volume lv_home successfully resized 

[root:coshina ~]# df -h 
文件系统              容量  已用  可用 已用%% 挂载点 
/dev/mapper/VolGroup-lv_root 
                       50G  2.9G   44G   7% / 
tmpfs                 5.9G  100K  5.9G   1% /dev/shm 
/dev/sda1             485M   37M  423M   8% /boot 
/dev/mapper/VolGroup-lv_home 
                       20G  172M   19G   1% /home

7.查看“Free PE / Size”剩余空间

[root:coshina ~]# vgdisplay 
  --- Volume group --- 
  VG Name               VolGroup 
  System ID              
  Format                lvm2 
  Metadata Areas        1 
  Metadata Sequence No  5 
  VG Access             read/write 
  VG Status             resizable 
  MAX LV                0 
  Cur LV                3 
  Open LV               3 
  Max PV                0 
  Cur PV                1 
  Act PV                1 
  VG Size               1.09 TiB 
  PE Size               4.00 MiB 
  Total PE              285022 
  Alloc PE / Size       19424 / 75.88 GiB 
  Free  PE / Size       265598 / 1.01 TiB 
  VG UUID               nSbflh-J7fN-xDvf-zLjL-tFcu-Y5Tm-ybnDk0

8.使用lvextend指令：扩展逻辑卷空间到/dev/mapper/VolGroup-lv_root目录下，也就是“/”目录下。

[root:coshina ~]# lvextend -L +1.01T /dev/mapper/VolGroup-lv_root 
  Rounding size to boundary between physical extents: 1.01 TiB 
  Extending logical volume lv_root to 1.06 TiB 
  Logical volume lv_root successfully resized

9.执行操作，使之生效，中间一定要耐心等待。

[root:coshina ~]# resize2fs -p /dev/mapper/VolGroup-lv_root 
resize2fs 1.41.12 (17-May-2010) 
Filesystem at /dev/mapper/VolGroup-lv_root is mounted on /; on-line resizing required 
old desc_blocks = 4,new_desc_blocks = 68 
Performing an on-line resize of /dev/mapper/VolGroup-lv_root to 284227584 (4k) blocks. 
The filesystem on /dev/mapper/VolGroup-lv_root is now 284227584 blocks long.

10.查看分区成功

[root:coshina ~]# df -h 
文件系统              容量  已用  可用 已用%% 挂载点 
/dev/mapper/VolGroup-lv_root 
                      1.1T  2.9G 1011G   1% / 
tmpfs                 5.9G  100K  5.9G   1% /dev/shm 
/dev/sda1             485M   37M  423M   8% /boot 
/dev/mapper/VolGroup-lv_home 
                       20G  172M   19G   1% /home

11.重启

[root:coshina ~]# shutdown -r now