3、将lv_home逻辑分区减小到指定大小
[root@CentOS-78 /]# lvreduce -L 282G /dev/mapper/vg_centos-lv_home
WARNING: Reducing active and open logical volume to 282.00 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 282.00 GiB
Logical volume lv_home successfully resized
[root@CentOS-78 /]#
我认为这个命令是将已经减少的100G空间拿到系统公共的区域，可以被其他分区加载和利用。
查询卷组的信息：
[root@CentOS-78 /]# vgdisplay
--- Volume group ---
VG Name vg_centos
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 5
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 465.27 GiB
PE Size 4.00 MiB
Total PE 119109
Alloc PE / Size 86472 / 337.78 GiB
Free PE / Size 32637 / 127.49 GiB
VG UUID 1k4ooN-RFV9-uyf1-uMYf-aERG-YaGs-ZNoSD6
Free PE / Size指定的应该是现在可在分配的空间。
4、增加vg_centos-lv_root分区的大小
将可用的空间添加到vg_centos-lv_root分区上面：
[root@CentOS-78 /]# lvextend -L +127.40G /dev/mapper/vg_centos-lv_root
Rounding up size to full physical extent 127.40 GiB
Extending logical volume lv_root to 177.40 GiB
Logical volume lv_root successfully resized
[root@CentOS-78 /]#
从新设定该分区的大小：
[root@CentOS-78 /]# resize2fs -p /dev/mapper/vg_centos-lv_root
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/mapper/vg_centos-lv_root is mounted on /; on-line resizing required
old desc_blocks = 4, new_desc_blocks = 12
Performing an on-line resize of /dev/mapper/vg_centos-lv_root to 46504960 (4k) blocks.
The filesystem on /dev/mapper/vg_centos-lv_root is now 46504960 blocks long.
5、再次查看分区大小
[root@CentOS-78 /]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_centos-lv_root
175G 14G 153G 9% /
tmpfs 1.9G 0 1.9G 0% /dev/shm
/dev/sda1 485M 37M 423M 8% /boot
/dev/mapper/vg_centos-lv_home
278G 663M 263G 1% /home
我们发现vg_centos-lv_root分区的空间已经增加了125G，之所以比lv_home减少的空间要多25G主要是由于我们把系统所有的可用的空间都加在了lv_root分区。