总体过程:

把/home内容备份,然后将/home文件系统所在的逻辑卷删除,扩大/root文件系统,新建/home ,恢复/home内容

1.查看分区

df -h

2.备份home分区文件

tar cvf /tmp/home.tar /home

3.卸载/home,如果无法卸载,先终止使用/home文件系统的进程

fuser -km /home/
umount /home 

4.删除/home所在的lv

lvremove /dev/mapper/centos-home

5.扩展/root所在的lv,增加800G

 lvextend -L +800G /dev/mapper/centos-root

6.扩展/root文件系统

xfs_growfs /dev/mapper/centos-root

7.重新创建home lv

lvcreate -L 73G -n /dev/mapper/centos-home 

8. 创建文件系统

 mkfs.xfs  /dev/mapper/centos-home

9.挂载home

mount /dev/mapper/centos-home

10.home文件恢复

tar xvf /tmp/home.tar -C /home/
cd /home/home/
mv * ../

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如果想创建额外的lvm

1. 查看vg

# vgscan
Reading volume groups from cache.
Found volume group "centos" using metadata type lvm2

# vgdisplay
--- Volume group ---
VG Name centos
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 7
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 <464.76 GiB
PE Size 4.00 MiB
Total PE 118978
Alloc PE / Size 39360 / 153.75 GiB
Free PE / Size 79618 / <311.01 GiB
VG UUID jKRX0T-8rz2-pRlV-ak5q-asSF-wT23-ldeCkV

2. 创建lv

# lvcreate -l 79618 -n mhc_lv centos

-l指定小于等于上边的 Free PE

# lvdisplay 

3. 格式化

# mkfs -t ext4 /dev/centos/mhc_lv

4. 挂载

# mkdir /data

# mount /dev/centos/mhc_lv /data