1.df -h查看使用情况

[root@localhost ~]# df -h
文件系统                 容量  已用  可用 已用% 挂载点
/dev/mapper/centos-root   45G   15G   30G   34% /
devtmpfs                 897M     0  897M    0% /dev
tmpfs                    912M     0  912M    0% /dev/shm
tmpfs                    912M  9.0M  903M    1% /run
tmpfs                    912M     0  912M    0% /sys/fs/cgroup
/dev/sda1               1014M  180M  835M   18% /boot
/dev/mapper/centos-home   22G   33M   22G    1% /home
tmpfs                    183M   20K  183M    1% /run/user/0
/dev/sr0                 4.3G  4.3G     0  100% /run/media/root/CentOS 7 x86_64

2.备份home目录到/boot目录（或其他目录也行，主要是为了以后还原）

[root@localhost ~]# alias cp='cp'
[root@localhost ~]# alias cp
alias cp='cp'
[root@localhost ~]# cp -rf  /home  /root/

3.查看备份的home目录

[root@localhost ~]# ls /root
anaconda-ks.cfg  initial-setup-ks.cfg  模板  图片  下载  桌面
home             公共                  视频  文档  音乐

4.取消/home的挂载

umount /home

5.删除之前home挂载的逻辑卷

[root@localhost ~]# lvremove /dev/mapper/centos-home
Do you really want to remove active logical volume centos/home? [y/n]: y
  Logical volume "home" successfully removed

6.扩展/root目录

物理上扩展10G

[root@localhost ~]# lvextend -L  +10G /dev/mapper/centos-root 
  Size of logical volume centos/root changed from <45.02 GiB (11524 extents) to <55.02 GiB (14084 extents).
  Logical volume centos/root successfully resized.

逻辑上设置跟物理边界一样大

[root@localhost ~]# xfs_growfs /dev/mapper/centos-root 
meta-data=/dev/mapper/centos-root isize=512    agcount=4, agsize=2950144 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0 spinodes=0
data     =                       bsize=4096   blocks=11800576, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal               bsize=4096   blocks=5762, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 11800576 to 14422016

7.重新创建home lv

[root@localhost ~]# lvcreate -L 10G -n /dev/mapper/centos-home
  Logical volume "home" created.

8.创建文件系统

[root@localhost ~]# mkfs.xfs /dev/mapper/centos-home 
meta-data=/dev/mapper/centos-home isize=512    agcount=4, agsize=655360 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0, sparse=0
data     =                       bsize=4096   blocks=2621440, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal log           bsize=4096   blocks=2560, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0

9.挂载home

[root@localhost ~]# mount /dev/mapper/centos-home /home

10.home文件恢复

[root@localhost ~]# cp  -rf /root/home/*  /home/
[root@localhost ~]# ls /home/
jy

11.查看root扩大后的磁盘情况

[root@localhost ~]# df -h
文件系统                 容量  已用  可用 已用% 挂载点
/dev/mapper/centos-root   55G   16G   40G   28% /
devtmpfs                 897M     0  897M    0% /dev
tmpfs                    912M     0  912M    0% /dev/shm
tmpfs                    912M  9.0M  903M    1% /run
tmpfs                    912M     0  912M    0% /sys/fs/cgroup
/dev/sda1               1014M  180M  835M   18% /boot
tmpfs                    183M   24K  183M    1% /run/user/0
/dev/sr0                 4.3G  4.3G     0  100% /run/media/root/CentOS 7 x86_64
/dev/mapper/centos-home   10G   33M   10G    1% /home