縮小 LV 標準作法

1. 查看要縮小 LV vg_kvm7home-vo 掛載在 /home，大小為 74M ( 80M )。

   [root@kvm7 ~]# df -h
   Filesystem                   Size  Used Avail Use% Mounted on
   /dev/mapper/vg_kvm7usb-root  3.1G  1.1G  1.8G  37% /
   devtmpfs                     487M     0  487M   0% /dev
   tmpfs                        497M     0  497M   0% /dev/shm
   tmpfs                        497M  6.6M  491M   2% /run
   tmpfs                        497M     0  497M   0% /sys/fs/cgroup
   /dev/vda1                    197M  107M   90M  55% /boot
   /dev/mapper/vg_kvm7home-vo    74M  1.6M   68M   3% /home
   /dev/mapper/vg_mnt-pub        24M     0   24M   0% /mnt/pub
   

2. 卸載 LV vg_kvm7home-vo。

   [root@kvm7 ~]# umount /dev/vg_kvm7home/vo
   

3. 先 resize LV vg_kvm7home-vo 檔案系統為 30M。

   [root@kvm7 ~]# resize2fs -f /dev/vg_kvm7home/vo 30M
   resize2fs 1.42.9 (28-Dec-2013)
   Resizing the filesystem on /dev/vg_kvm7home/vo to 30720 (1k) blocks.
   The filesystem on /dev/vg_kvm7home/vo is now 30720 blocks long.
   

4. 再 resize LV vg_kvm7home-vo 為 30M， 縮小時此命令一定要在 resize2fs 命令之後執行，放大時則順序相反。

   [root@kvm7 ~]# lvresize -L 30M /dev/vg_kvm7home/vo 
     WARNING: Reducing active logical volume to 30.00 MiB
     THIS MAY DESTROY YOUR DATA (filesystem etc.)
   Do you really want to reduce vo? [y/n]: y
     Size of logical volume vg_kvm7home/vo changed from 80.00 MiB (40 extents) to 30.00 MiB (15 extents).
     Logical volume vo successfully resized
   

5. 再檢查 LV vg_kvm7home-vo 大小為 24M ( 30M )。

   [root@kvm7 ~]# df -h
   Filesystem                   Size  Used Avail Use% Mounted on
   /dev/mapper/vg_kvm7usb-root  3.1G  1.1G  1.8G  37% /
   devtmpfs                     487M     0  487M   0% /dev
   tmpfs                        497M     0  497M   0% /dev/shm
   tmpfs                        497M  6.6M  491M   2% /run
   tmpfs                        497M     0  497M   0% /sys/fs/cgroup
   /dev/vda1                    197M  107M   90M  55% /boot
   /dev/mapper/vg_mnt-pub        24M     0   24M   0% /mnt/pub
   /dev/mapper/vg_kvm7home-vo    25M  784K   23M   4% /home