ubuntu@ubuntu:~$ sudo fdisk -l

Disk /dev/sda: 12.6 GB, 12582912000 bytes
255 heads, 63 sectors/track, 1529 cylinders, total 24576000 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: 0x000e3443

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048      499711      248832   83  Linux
/dev/sda2          501758    24575999    12037121    5  Extended
/dev/sda5          501760    24573951    12036096   8e  Linux LVM
ubuntu@ubuntu:~$ sudo resize2fs /dev/sda2 12000M
resize2fs 1.42.9 (4-Feb-2014)
resize2fs: Attempt to read block from filesystem resulted in short read while trying to open /dev/sda2
Couldn't find valid filesystem superblock.
ubuntu@ubuntu:~$