Install parted \\
root@matrix:/home/sunkan# aptitude install parted

Run partprobe on the blockdevice
<code>
root@matrix:/home/sunkan# blockdev --getsize64 /dev/xvde
21474836480
root@matrix:/home/sunkan# partprobe /dev/xvde
root@matrix:/home/sunkan# blockdev --getsize64 /dev/xvde
42949672960
</code>