Linux在线收缩lvm逻辑卷

我们在使用LINUX系统时候，如果需要将一个已经挂载使用中的分区进行容量缩小，将腾出的容量划分成其他分区，需要怎么做呢？下面为Linux在线收缩lvm逻辑卷的详细步骤（前提是此lvm的剩余空间能足够缩小至操作值）：
1.卸载
#touch /opt/test.txt -->测试写入一些文件
#umount /opt

2.文件系统检查

fsck -f /dev/mapper/VolGroup00-LogVol00_opt

fsck 1.39 (29-May-2006)
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/mapper/VolGroup00-LogVol00_opt: 41641/135479296 files (0.7% non-contiguous), 31756336/270958592 blocks

3.调整文件系统的大小
resize2fs /dev/mapper/VolGroup00-LogVol00_opt 500G

–>将VolGroup00-LogVol00_opt瘦小到500G*

resize2fs 1.39 (29-May-2006)
Resizing the filesystem on /dev/mapper/VolGroup00-LogVol00_opt to 131072000 (4k) blocks.
The filesystem on /dev/mapper/VolGroup00-LogVol00_opt is now 131072000 blocks long.

4.裁减逻辑卷
lvreduce -L 500G /dev/mapper/VolGroup00-LogVol00_opt

  WARNING: Reducing active logical volume to 500.00 GB
  THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce LogVol00_opt? [y/n]: y
  Reducing logical volume LogVol00_opt to 500.00 GB
  Logical volume LogVol00_opt successfully resized

5.再次检查文件系统是否出现错误
fsck -f /dev/mapper/VolGroup00-LogVol00_opt

fsck 1.39 (29-May-2006)
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: Chaaaaecking group summary information
/dev/mapper/VolGroup00-LogVol00_opt: 41641/65536000 files (0.7% non-contiguous), 29561045/131072000 blocks

6.挂载
mount -t ext3 /dev/mapper/VolGroup00-LogVol00_opt /opt

 df -h
/dev/mapper/VolGroup00-LogVol00_orabak 493G 198M 467G 1% /orabak
Yau's 10:44:54

7.另外LVM在线扩容操作：

lvextend -n /dev/mapper/VolGroup00-orabak -L +100G
resize2fs /dev/mapper/VolGroup00-ora