[pve-devel] [PATCH v3 qemu-server 11/11] qcow2: add external snapshot support

[DERUMIER, Alexandre]

Hi Fabio !

>>
>>In this implementation I don't see the possibility of using them on
>>raw 
>>disks (on files) from a fast look, or am I wrong? If so, why? I think
>>the main use would be in cases like that where you don't have
>>snapshot 
><support by default

Ah, we have discussed about it with Fabian. the V1/v2 had raw support,
but I have removed it from v3 because it's simplify a lot the code,
and from my test, I don't see anymore too much difference between qcow2
&& raw. (maybe 10% diff max)

Note that you can preallocated 100% the base qcow2 image if you want.
(or only metadatas, that's the defaut)


I'm going to do more extensive benchmark, but qcow2 have improved a lot
since last years (with sub-allocation clusters), so it should be too
far from a cow filesystem like zfs,btrfs. (sure, they are still
overhead vs a simple raw).