Do you hate how Centos 7 defaults to allocating most of your valuable space to /home even though it is a production server?
Here is a quick guide on how to take back that space live, while online (of course make sure you have backups just in case something goes wrong!):
First we will reduce our home dir by 100G:
lvreduce -L -100G /dev/mapper/centos-home
WARNING: Reducing active and open logical volume to ........
In short the solution is just to use vgremove for the actual /dev/mapper device:
vgremove /dev/mapper/backups-backuplv
box mnt # mdadm --manage /dev/md8 --stop
mdadm: Cannot get exclusive access to /dev/md8:Perhaps a running process, mounted filesystem or active volume group?
box mnt # lv
lvchange lvconvert lvcreate l........
lvextend -L +10G /dev/kvmvm/w2k8r2evalstandard
Extending logical volume w2k8r2evalstandard to 20.00 GiB
Logical volume w2k8r2evalstandard successfully resized
The above adds 10GB to the logical volume. Of course you must resize the filesystem using other tools to take advantage of the space.........