Add some physical or virtual storage (resize a VM image, add a new VM image, add a disk)
Create a new LVM physical volume
lvm pvcreate /dev/sdb # substitute appropriate device name
Figure out the volume group name:
lvm vgdisplay
Add the physical volume to the volume group
lvm vgextend debian8-taldev-vg /dev/sdb
Figure out the name of the logical volume you wish to enlarge
lvm lvdisplay
Resize the logical volume
lvm lvextend -l +100%FREE /dev/debian8-taldev-vg/root
Resize the filesystem
For extX:
resize2fs /dev/debian8-taldev-vg/root
For BtrFS
btrfs filesystem resize max /