参考：CSDN博主「evandeng2009」的原创文章，遵循CC 4.0 BY-SA版权协议
原文链接：https://blog.csdn.net/evandeng2009/article/details/49814097
事件：CentOS 7默认安装时/home占用太多空间，根目录相较而言就小得多(只有50G)
步骤：
- 备份/home/用户文件
- umount /home 卸载并lvremove删除这个home逻辑卷，释放它的空间，vgdisplay查看卷组可用空间大小
- lvcreate新建一个新的home卷，并在其上mkfs建立xfs文件系统，(分配挂载到/home - 不用更改/etc/fstab，重启即可，) 拷贝回来之前的内容
(这个时候空余的空间随便你分配，可以再建立别的逻辑卷，或者直接空闲下来以后使用，也可以直奔主题的走下面的第四步) - 把之前的home逻辑卷释放并分配新卷home之后剩下的空间，lvextend分配给root卷，并用命令xfs_growfs扩展它的文件系统空间
操作命令
- 备份/home中的用户数据
[root@localhost /]# mkdir /backup && mv /home/* /backup
[root@localhost /]# ls /home/
- 卸载/home并删除逻辑卷home
[root@localhost /]# umount /home #卸载/home
[root@localhost /]# lvremove /dev/centos/home #删除逻辑卷home
Do you really want to remove active logical volume home? [y/n]: y
Logical volume "home" successfully removed
[root@localhost /]# vgdisplay #查看卷组可用空间
--- 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 2
Open LV 2
Max PV 0
Cur PV 1
Act PV 1
VG Size 931.02 GiB
PE Size 4.00 MiB
Total PE 238341
Alloc PE / Size 14784 / 57.75 GiB
Free PE / Size 223557 / 873.27 GiB
VG UUID IFQnYm-fCLh-38mD-Duid-nYXQ-qktX-3F1a
#Free PE / Size 中显示的空间为卷组的空闲空间873G，之前为64M，也就是刚才删除的逻辑卷home所占用的空间，我们就从这个当中拿出一部分比如50G作为home
- 新建一个卷home，挂载到/home
[root@localhost /]# lvcreate -L 50G -n home centos #L表示大小，默认单位为M；n表示卷名；这里的centos是CentOS7安装系统的时候就默认建立好的卷组名
WARNING: xfs signature detected on /dev/centos/home at offset 0. Wipe it? [y/n]: y
Wiping xfs signature on /dev/centos/home.
Logical volume "home" created.
[root@localhost /]# lvdisplay #查看逻辑卷home
--- Logical volume ---
LV Path /dev/centos/home
LV Name home
VG Name centos
LV UUID b5lLlv-FQPY-dT43-SmzV-sSLA-4QqP-gdQqAP
LV Write Access read/write
LV Creation host, time localhost, 2015-11-13 14:05:06 +0800
LV Status available
# open 0
LV Size 50.00 GiB
Current LE 12800
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:2
[root@localhost /]# vgdisplay #再次查看卷组空间大小
--- Volume group ---
VG Name centos
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 8
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 3
Open LV 2
Max PV 0
Cur PV 1
Act PV 1
VG Size 931.02 GiB
PE Size 4.00 MiB
Total PE 238341
Alloc PE / Size 27584 / 107.75 GiB
Free PE / Size 210757 / 823.27 GiB
VG UUID IFQnYm-fCLh-38mD-Duid-nYXQ-qktX-3F1atk
[root@localhost /]# vgchange -ay centos #可选步骤：激活卷组centos，使得这个新建的home逻辑卷生效（用vgchange而不用lvchange）]
3 logical volume(s) in volume group "centos" now active
[root@localhost /]# mkfs -t xfs /dev/centos/home #在新建的逻辑卷home上建立xfs文件系统
meta-data=/dev/centos/home isize=256 agcount=4, agsize=3276800 blks
= sectsz=4096 attr=2, projid32bit=1
= crc=0 finobt=0
data = bsize=4096 blocks=13107200, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=0
log =internal log bsize=4096 blocks=6400, version=2
= sectsz=4096 sunit=1 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
[root@localhost /]# mount /dev/centos/home /home/ #把这个新逻辑卷home挂到之前的文件夹/home中去，直接重启用fstab来挂载也行
[root@localhost /]# df -h #查看磁盘使用情况
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/centos-root 50G 17G 34G 33% /
devtmpfs 3.9G 0 3.9G 0% /dev
tmpfs 3.9G 84K 3.9G 1% /dev/shm
tmpfs 3.9G 9.0M 3.9G 1% /run
tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup
/dev/sda1 494M 133M 362M 27% /boot
/dev/mapper/centos-home 50G 33M 50G 1% /home
[root@localhost /]# mv /backup/* /home/
- 最后再把释放出来多余的空间分配给root卷并xfs_growfs扩展文件系统
[root@localhost /]# lvextend -L +823G /dev/centos/root #把剩下的823G现在分配给root卷，剩下那点渣渣空间让它闲着；+号表示在原来的基础上额外增加，不要+则设定为具体额度
Size of logical volume centos/root changed from 50.00 GiB (12800 extents) to 873.00 GiB (223488 extents).
Logical volume root successfully resized
[root@localhost /]# lvdisplay #查看逻辑卷和卷组情况，这下root的空间就多达到873G，之前的是50G
--- Logical volume ---
LV Path /dev/centos/root
LV Name root
VG Name centos
LV UUID PgscNL-rvyY-21Z1-tVe3-80vC-ONCw-VlvmYs
LV Write Access read/write
LV Creation host, time localhost, 2015-11-11 04:46:04 +0800
LV Status available
# open 1
LV Size 873.00 GiB
Current LE 223488
Segments 2
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
[root@localhost /]# vgchange -ay centos #再次激活下卷组centos
[root@localhost /]#df -h #不使用xfs_growfs扩展文件系统，磁盘是不认得多的空间的
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/centos-root 50G 4.8G 46G 10% /
devtmpfs 3.9G 0 3.9G 0% /dev
tmpfs 3.9G 140K 3.9G 1% /dev/shm
tmpfs 3.9G 9.0M 3.9G 1% /run
tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup
/dev/sda1 494M 133M 362M 27% /boot
/dev/mapper/centos-home 50G 12G 39G 23% /home
[root@localhost /]# xfs_growfs /dev/centos/root #扩展root卷
[root@localhost /]# df -h #再看root大小已经生效，800多G了
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/centos-root 873G 4.8G 869G 1% /
devtmpfs 3.9G 0 3.9G 0% /dev
tmpfs 3.9G 140K 3.9G 1% /dev/shm
tmpfs 3.9G 9.0M 3.9G 1% /run
tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup
/dev/sda1 494M 133M 362M 27% /boot
/dev/mapper/centos-home 50G 12G 39G 23% /home
Centos7 ext3/4 xfs扩容根分区(非LVM)
https://blog.51cto.com/890909/2528584?source=drt