expanding LVM partition

I have a server that's running low on space, but it seems like it's just not been allocated properly. Can I use LVM to do something with the system while it's running, or do I have to have partitions unmounted to expand? Should I be using gparted?

Thanks

output of df -h

Filesystem Size Used Avail Use% Mounted on rootfs 17G 12G 4.4G 73% / udev 10M 0 10M 0% /dev tmpfs 202M 168K 202M 1% /run /dev/mapper/turnkey-root 17G 12G 4.4G 73% / tmpfs 5.0M 0 5.0M 0% /run/lock tmpfs 403M 148K 403M 1% /run/shm /dev/sda1 415M 22M 372M 6% /boot 

output of fdisk -l

Disk /dev/sda: 107.4 GB, 107374182400 bytes 255 heads, 63 sectors/track, 13054 cylinders, total 209715200 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000c1209 Device Boot Start End Blocks Id System /dev/sda1 * 122880 999423 438272 83 Linux /dev/sda2 1001472 39061503 19030016 8e Linux LVM /dev/sda3 39061504 209715199 85326848 83 Linux Disk /dev/mapper/turnkey-root: 105.2 GB, 105226698752 bytes 255 heads, 63 sectors/track, 12793 cylinders, total 205520896 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/mapper/turnkey-root doesn't contain a valid partition table Disk /dev/mapper/turnkey-swap_1: 536 MB, 536870912 bytes 255 heads, 63 sectors/track, 65 cylinders, total 1048576 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/mapper/turnkey-swap_1 doesn't contain a valid partition table 

output of lsblk

NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 100G 0 disk |-sda1 8:1 0 428M 0 part /boot |-sda2 8:2 0 18.2G 0 part | |-turnkey-root (dm-0) 254:0 0 98G 0 lvm / | `-turnkey-swap_1 (dm-1) 254:1 0 512M 0 lvm [SWAP] `-sda3 8:3 0 81.4G 0 part `-turnkey-root (dm-0) 254:0 0 98G 0 lvm / sr0 11:0 1 1024M 0 rom 

output of vgs

VG #PV #LV #SN Attr VSize VFree turnkey 2 2 0 wz--n- 99.52g 1.02g 

output of lvs

LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert root turnkey -wi-ao-- 98.00g swap_1 turnkey -wi-ao-- 512.00m