需求：Linux根目录太小，不满足使用要求，需要将/home下磁盘空间转移部分给根目录
目标：将/home下341G空间，转移到根目录下200G
操作步骤：
查看磁盘空间大小，/home下容量341G，使用8.8G，/根目录容量50G，使用28G
[
root@244 ~]#
df -h
文件系统 容量 已用 可用 已用%% 挂载点
/dev/mapper/vg_244-lv_root 50G 28G 19G 60% /
tmpfs 499M 0 499M 0% /dev/shm
/dev/sda1 485M 162M 298M 36% /boot
/dev/mapper/vg_244-lv_home 341G 8.8G 315G 3% /home
卸载/home
[
root@244 /]#
umount /home
umount /home 如果提示无法卸载，则是有进程占用/home，使用如下命令来终止占用进程：
[
root@244 /]#
fuser -m /home
查看/home已经被卸载掉了
[
root@244 /]#
df -h
文件系统 容量 已用 可用 已用%% 挂载点
/dev/mapper/vg_244-lv_root 50G 28G 19G 60% /
tmpfs 499M 0 499M 0% /dev/shm
/dev/sda1 485M 162M 298M 36% /boot
调整分区大小到150G
resize2fs命令被用来增大或者收缩未加载的“ext2/ext3”文件系统的大小。如果文件系统是处于mount状态下，那么它只能做到扩容，前提条件是内核支持在线resize
[
root@244 /]#
resize2fs -p /dev/mapper/vg_244-lv_home 150G
resize2fs 1.42.2 (27-Mar-2012)
Please run 'e2fsck -f /dev/mapper/vg_244-lv_home' first.
根据提示，需要先执行e2fsck
[
root@244 /]#
e2fsck -f /dev/mapper/vg_244-lv_home
e2fsck 1.42.2 (27-Mar-2012)
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/vg_244-lv_home: 13478/22650880 files (0.2% non-contiguous), 2563008/90589184 blocks
执行完毕，再执行resize2fs
[
root@244 /]#
resize2fs -p /dev/mapper/vg_244-lv_home 150G
resize2fs 1.42.2 (27-Mar-2012)
Resizing the filesystem on /dev/mapper/vg_244-lv_home to 39321600 (4k) blocks.
Begin pass 2 (max = 160645)
Relocating blocks XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Begin pass 3 (max = 2765)
Scanning inode table XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Begin pass 4 (max = 1419)
Updating inode references XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The filesystem on /dev/mapper/vg_244-lv_home is now 39321600 blocks long.
挂载/home，查看磁盘
[
root@244 /]#
mount /home/
[
root@244 /]#
df -h
文件系统 容量 已用 可用 已用%% 挂载点
/dev/mapper/vg_244-lv_root 50G 28G 19G 60% /
tmpfs 499M 0 499M 0% /dev/shm
/dev/sda1 485M 162M 298M 36% /boot
/dev/mapper/vg_244-lv_home 148G 4.4G 136G 4% /home
[
root@244 /]#
lvreduce -L 150G /dev/mapper/vg_244-lv_home
WARNING: Reducing active and open logical volume to 150.00 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 150.00 GiB
Logical volume lv_home successfully resized
[
root@244 /]#
lvextend -L +200G /dev/mapper/vg_244-lv_root
Extending logical volume lv_root to 250.00 GiB
Insufficient free space: 51200 extents needed, but only 50066 available
[
root@244 /]# lvextend -L +100G /dev/mapper/vg_244-lv_root
Extending logical volume lv_root to 150.00 GiB
Logical volume lv_root successfully resized
[
root@244 /]#
resize2fs -p /dev/mapper/vg_244-lv_root
resize2fs 1.42.2 (27-Mar-2012)
Filesystem at /dev/mapper/vg_244-lv_root is mounted on /; on-line resizing required
old_desc_blocks = 4, new_desc_blocks = 16
Performing an on-line resize of /dev/mapper/vg_244-lv_root to 64374784 (4k) blocks.
The filesystem on /dev/mapper/vg_244-lv_root is now 64374784 blocks long.
[
root@244 /]#
df -h
文件系统 容量 已用 可用 已用%% 挂载点
/dev/mapper/vg_244-lv_root
242G 28G 202G 13% /
tmpfs 499M 0 499M 0% /dev/shm
/dev/sda1 485M 162M 298M 36% /boot
/dev/mapper/vg_244-lv_home
148G 4.4G 136G 4% /home
[
root@244 /]#