[Qemu-devel] help me with qemu-img theory(snapshot and backing file)

[yue-kvm]

hi,all
if there any documents about snapshot and backing file's  theory.
as we know vmware has composor which can upgrade images(top of backing chain ) 
by upgrading backing file
 
so i think we can implement it anyway.
 
now i need some infomations  relevant to my idea.
and hope qemu-img developer guys can work together with me to finish this 
feature.
 
thanks.