第一步：逻辑卷的缩减，有风险，先缩减逻辑边界——再缩减物理边界
注意：1、不能在线缩减，得先卸载；
2、确保缩减后的空间大小依然能存储原有的所有数据；
3、在缩减之前应该强行检查文件，确保文件系统处于一致性状态
df –lh
umount 卸载
e2fsck -f /PATH/TO/PV 强行文件系统检查，看是否有问题
开始缩减
用lvdisplay命令查看逻辑卷消息
resize2fs /PATH/TO/PV 50G
缩减(逻辑边界)为50G （缩减后的总共大小为50G）
lvreduce -L [-]# /PATH/TO/LV
缩减(物理边界)为50G
mount -a
重新挂在
下面为实际操作过程及结果：
[[email protected] ~]# umount /dev/vg_wlm2/lv_home
[[email protected] ~]# resize2fs /dev/vg_wlm2/lv_home 50G
resize2fs 1.41.12 (17-May-2010)
The filesystem is already 13107200 blocks long. Nothing to do!
[[email protected] ~]# lvreduce -L 50G /dev/vg_wlm2/lv_home
WARNING: Reducing active logical volume to 50.00 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 50.00 GiB
Logical volume lv_home successfully resized
[[email protected] ~]# mount -a
[[email protected] ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_wlm2-lv_root 50G 38G 8.8G 82% /
tmpfs 1.4G 144K 1.4G 1% /dev/shm
/dev/sda1 485M 40M 420M 9% /boot
/dev/mapper/vg_wlm2-lv_home 50G 23G 25G 49% /home
注意：lv的物理路径要用lvdisplay查看，用df查看的只是挂载点
第二步：逻辑卷的扩张：先扩张物理边界———再扩张逻辑边界
扩张物理边界
命令：lvextend
-L [+]# /PATH/TO/LV
扩展逻辑边界
resize2fs
resize2fs -p /PATH/TO/LV
注意：过程有点长，正常现象
下面为实际操作过程及结果：
[[email protected] ~]# lvextend -L 400G /dev/vg_wlm2/lv_root
Extending logical volume lv_root to 400.00 GiB
Logical volume lv_root successfully resized
You have new mail in /var/spool/mail/root
[[email protected] ~]# resize2fs -p /dev/vg_wlm2/lv_root
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/vg_wlm2/lv_root is mounted on /; on-line resizing required
old desc_blocks = 4, new_desc_blocks = 25
Performing an on-line resize of /dev/vg_wlm2/lv_root to 104857600 (4k) blocks.
The filesystem on /dev/vg_wlm2/lv_root is now 104857600 blocks long.
You have new mail in /var/spool/mail/root
