Linux command line ninjas can check the size of their Inspiron Mini's partition by following a few simple steps. Open a terminal and enter the sudo fdisk -l command, and enter your password. You'll be greeted with the image above, as well an accurate size of your partition.
Dell, for its part, is shipping updated machines that fix this issue. Existing owners looking for a fix have a few options, says Liliputing:
If you have a USB DVD drive, you can use the system restore disc to reinstall Dell's custom version of Ubuntu. It will reformat the entire drive.
Or you can attempt to resize your partitions. The easiest way to do this is probably to download and install Parted Magic to a USB flash drive and then boot from that drive. Run the gParted partition manager and you should see the 4GB partition that Ubuntu is installed on and 8 or 12GB of unused space. Just grab the edge of the 4GB partition and drag it resize the partition, save your changes and reboot.
Of course, these DIY fixes run the chance of erasing your OS, so maybe this is one of those customer support times. Unless you live and breathe Ubuntu. Then, by all means, hack away.