I have used partimage on occasion to backup my disk, however one of the issues that used to get me was after restoring an image to a new partition of a larger size the partition would show as the old size.

Here are the steps to resolve this issue.

WARNING: Before making any changes to disks you should back up your data first!

1) Boot you system with a LIVE CDROM or USB STICK using a rescue linux  such as Partition Magic.

2) Boot from the LIVE CD / USB device.

3) Open a terminal session, and type the following.

# df -h

Ensure no partitions are mounted if they are use the command below. (replace x with your partition number)

# umount /dev/sdax

4) Run a file system check to ensure it integrity before making any changes.

# fsck -n /dev/sda3

Output should like something like below.

/dev/sda3: clean, <SOMESIZE>>

5) Remove the journal from /dev/sdax, this will make it an ext2 partition and allow the resize commands to work their magic.

# tune2fs -O ^has_journal /dev/sdax

6) Run another file system check.

# e2fsck -f /dev/sdax

7) Resize the partition with resize2fs without options will use the max size of the disk / partition

# resize2fs /dev/sdax

8.) Now run another filesystem check.

# fsck -n /dev/sdax

9) Create journal on /dev/sdax, this will turn sdax from a ext2 to a ext3 partition again

# tune2fs -j /dev/sdax
10 ) To check it has worked mount the partition and check it's size as follows:
# mount /dev/sdax /mnt
# df -h

11) Reboot the system.