growing virtual disks
Lots of people, in order to increase virtual disk size, underestimate
the power of
dd and start creating other images, copying data
or concatenating raw files.
Suppose you have a 4G image and you want to increase its size to 8G,
IMHO the simplest way is:
dd if=/dev/zero of=myoriginalsmallimage bs=1 count=1 seek=8G
That's all.