[root@CentOS-78 /]# df -h 
Filesystem      Size Used Avail Use% Mounted on 
/dev/mapper/vg_centos-lv_root 
            50G  14G  34G 30% / 
tmpfs         1.9G   0 1.9G  0% /dev/shm 
/dev/sda1       485M  37M 423M  8% /boot 
/dev/mapper/vg_centos-lv_home 
           404G 670M 382G  1% /home 

[root@CentOS-78 /]# umount /home 

[root@CentOS-78 /]# df -h 
Filesystem      Size Used Avail Use% Mounted on 
/dev/mapper/vg_centos-lv_root 
            50G  14G  34G 30% / 
tmpfs         1.9G   0 1.9G  0% /dev/shm 
/dev/sda1       485M  37M 423M  8% /boot 

[root@CentOS-78 /]# resize2fs -p /dev/mapper/vg_centos-lv_home 282G 
resize2fs 1.41.12 (17-May-2010) 
Please run 'e2fsck -f /dev/mapper/vg_centos-lv_home' first. 

[root@CentOS-78 /]# e2fsck -f /dev/mapper/vg_centos-lv_home 
e2fsck 1.41.12 (17-May-2010) 
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_centos-lv_home: 1386/26836992 files (0.9% non-contiguous), 1855856/107344896 blocks 

[root@CentOS-78 /]# resize2fs -p /dev/mapper/vg_centos-lv_home 282G 
resize2fs 1.41.12 (17-May-2010) 
Resizing the filesystem on /dev/mapper/vg_centos-lv_home to 73924608 (4k) blocks. 
Begin pass 2 (max = 43) 
Relocating blocks       XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 
Begin pass 3 (max = 3276) 
Scanning inode table     XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 
Begin pass 4 (max = 266) 
Updating inode references   XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 
The filesystem on /dev/mapper/vg_centos-lv_home is now 73924608 blocks long. 

[root@CentOS-78 /]# mount /home 
[root@CentOS-78 /]# 
[root@CentOS-78 /]# df -h 
Filesystem      Size Used Avail Use% Mounted on 
/dev/mapper/vg_centos-lv_root 
            50G  14G  34G 30% / 
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 
[root@CentOS-78 /]# 

[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"htmlcode">

[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。


三、所遇到的问题
1、在卸载/home目录的时候失败
可先执行如下fuser命令，然后再umount即可：


[root@CentOS-78 /]# fuser -m /home 
[root@CentOS-78 /]# 


2、设定完lv_home的大小，再次mount该分区时，发现用df命令无法看到给分区，此时只要在mount一次即可


3、在设定lv_root的大小时，不要把Free PE / Size的空间全部都用上，这很可能会出现Free PE空间不足的现象，建议保留一点Free PE的空间。
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。