一/先查看当前的 根分区 大小为21G
[root@test-disk ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00 21G 960M 19G 5% /
/dev/mapper/VolGroup00-LogVol02 7.6G 151M 7.3G 2% /home
/dev/hda1 99M 12M 82M 13% /boot
tmpfs 189M 0 189M 0% /dev/shm
二/插入系统光盘,启动后输入linux rescue进去救援模式,不要配置网络,不要让系统根挂载到/mnt/sysimage上,  的界面选择“skip”
分别为：查看物理卷 查看卷组 查看逻辑卷 激活逻辑卷
三/开始减小根文件系统大小
四/减小根lv大小
此时得出LogVol00的LE数量为682,总的PE数量为956,大小32M,可以减少的大小为
（956-682）*32M=8768M
五/重启进去系统,再次查看根分区情况
[root@test-disk ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00 13G 956M 12G 8% /
/dev/mapper/VolGroup00-LogVol02 7.6G 151M 7.3G 2% /home
/dev/hda1 99M 12M 82M 13% /boot
tmpfs 189M 0 189M 0% /dev/shm
[root@test-disk ~]# vgdisplay 查看卷组情况
--- Volume group ---
VG Name VolGroup00
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 10
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 29.88 GB
PE Size 32.00 MB
Total PE 956
Alloc PE / Size 682 / 21.31 GB
Free PE / Size 274 / 8.56 GB
VG UUID l6vUxv-U8KC-gVdH-RQH5-QuUC-jsdl-HjpVqN
[root@test-disk ~]# lvdisplay /dev/VolGroup00/LogVol00
--- Logical volume ---
LV Name /dev/VolGroup00/LogVol00
VG Name VolGroup00
LV UUID Nbcfw3-7jG7-URyG-fRdl-5k6j-x0BC-EFpt0J
LV Write Access read/write
LV Status available
# open 1
LV Size 12.75 GB
Current LE 408
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
六/把从根分区减出的添加到/home
[root@test-disk ~]# umount /home/
[root@test-disk ~]# e2fsck -f /dev/VolGroup00/LogVol02
e2fsck 1.39 (29-May-2006)
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/VolGroup00/LogVol02: 11/2064384 files (9.1% non-contiguous), 103072/2048000 blocks
[root@test-disk ~]# lvextend -l 274 /dev/VolGroup00/LogVol02
/dev/cdrom: open failed:
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