I attempted to use lvextend to enlarge the main partition to use up the rest of the space on the disk (about 10GB more), but it seems to have not worked, with system monitor and df still reporting the original size (about 9GB).
lvdisplay
--- Logical volume ---
LV Path /dev/ubuntu-vg/root
LV Name root
VG Name ubuntu-vg
LV UUID d8r0nV-xVlJ-h1gA-QCaa-hXYg-71Aq-orkCu6
LV Write Access read/write
LV Creation host, time ubuntu, 2014-05-15 20:52:28 +0100
LV Status available
# open 1
LV Size 18.76 GiB
Current LE 4802
Segments 2
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 252:0
df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/mapper/ubuntu--vg-root 8907816 3835428 4596844 46% /
Did I miss something?