[root@localhost mysql-5.5.16]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
                       50G  3.2G   44G   7% /
tmpfs                  24G     0   24G   0% /dev/shm
/dev/sda1             485M   36M  424M   8% /boot
/dev/mapper/VolGroup-lv_home
                     1018G  200M  966G   1% /home
 
将/dev/mapper/VolGroup-lv_home减少到200G    
[root@localhost mysql-5.5.16]# umount /home/

检查文件系统的正确性
[root@localhost mysql-5.5.16]# e2fsck -f /dev/mapper/VolGroup-lv_home
e2fsck 1.41.12 (17-May-2010)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/mapper/VolGroup-lv_home: 16/67756032 files (0.0% non-contiguous), 4303548/271008768 blocks

设置lv /dev/mapper/VolGroup-lv_home使用空间为200G
[root@localhost mysql-5.5.16]# resize2fs /dev/mapper/VolGroup-lv_home 200G
resize2fs 1.41.12 (17-May-2010)
Resizing the filesystem on /dev/mapper/VolGroup-lv_home to 52428800 (4k) blocks.
The filesystem on /dev/mapper/VolGroup-lv_home is now 52428800 blocks long.


[root@localhost mysql-5.5.16]# mount /dev/mapper/VolGroup-lv_home /home
[root@localhost mysql-5.5.16]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
                       50G  3.2G   44G   7% /
tmpfs                  24G     0   24G   0% /dev/shm
/dev/sda1             485M   36M  424M   8% /boot
/dev/mapper/VolGroup-lv_home
                     197G  188M  187G   1% /home

实际lv空间没变
[root@localhost mysql-5.5.16]# lvdisplay
  --- Logical volume ---
  LV Name                /dev/VolGroup/lv_root
  VG Name                VolGroup
  LV UUID                PIwK7O-7EEb-bmUL-1GE3-kEq6-ubnX-02x31A
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                50.00 GiB
  Current LE             12800
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:0
   
  --- Logical volume ---
  LV Name                /dev/VolGroup/lv_home
  VG Name                VolGroup
  LV UUID                vybuOS-H6RN-lMLa-fyet-Tcwr-O5P6-pDV5YY
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                1.01 TiB
  Current LE             264657
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:2

将lv_home800G空间释放出来
[root@localhost mysql-5.5.16]# lvresize -L -800G /dev/VolGroup/lv_home
  WARNING: Reducing active and open logical volume to 233.82 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 233.82 GiB
  Logical volume lv_home successfully resized


[root@localhost mysql-5.5.16]# lvdisplay
  --- Logical volume ---
  LV Name                /dev/VolGroup/lv_root
  VG Name                VolGroup
  LV UUID                PIwK7O-7EEb-bmUL-1GE3-kEq6-ubnX-02x31A
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                50.00 GiB
  Current LE             12800
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:0
   
  --- Logical volume ---
  LV Name                /dev/VolGroup/lv_home
  VG Name                VolGroup
  LV UUID                vybuOS-H6RN-lMLa-fyet-Tcwr-O5P6-pDV5YY
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                233.82 GiB
  Current LE             59857
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:2
   
  --- Logical volume ---
  LV Name                /dev/VolGroup/lv_swap
  VG Name                VolGroup
  LV UUID                GRyv7s-Pl4g-Fu2m-PzNp-bDdg-4k2e-hGVtS2
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                33.45 GiB
  Current LE             8564
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:1
   
查看空闲空间
[root@localhost mysql-5.5.16]# vgs
  VG       #PV #LV #SN Attr   VSize VFree  
  VolGroup   1   3   0 wz--n- 1.09t 800.00g

将全部空闲空间分给/dev/mapper/VolGroup-lv_root
[root@localhost mysql-5.5.16]# lvextend -l +100%FREE /dev/mapper/VolGroup-lv_root
  Extending logical volume lv_root to 850.00 GiB


[root@localhost mysql-5.5.16]# resize2fs /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 = 54
Performing an on-line resize of /dev/mapper/VolGroup-lv_root to 222822400 (4k) blocks.
The filesystem on /dev/mapper/VolGroup-lv_root is now 222822400 blocks long.


[root@localhost mysql-5.5.16]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
                      837G  3.2G  792G   1% /
tmpfs                  24G     0   24G   0% /dev/shm
/dev/sda1             485M   36M  424M   8% /boot
/dev/mapper/VolGroup-lv_home
                      197G  188M  187G   1% /home

步骤完成。若要求为减少lv_home的空间，增加到新建的lv中，步骤如下：
1.先执行到上述步骤的：
将lv_home800G空间释放出来
[root@localhost mysql-5.5.16]# lvresize -L -800G /dev/VolGroup/lv_home

2.新建lv
[root@localhost mysql-5.5.16]# lvcreate -L 800G -n data /dev/VolGroup
Logical volume "data" created

3.格式化LV逻辑卷为ext3文件系统格式

[root@localhost mysql-5.5.16]# mkfs.ext3 /dev/VolGroup/data

4.mount即可