[pve-devel] snapshot improvements

[Dietmar Maurer]

> How is it possible to save the vmstate if the vm is not paused ? (with a lot a
> memory write access by example ?)

I currently allocate am image equal to the size of the VM memory.

Then I simply do an incremental state save (like a vm migration), and keep
the VM running until (saved_bytes + remaining_bytes < available_space).

This is not perfect, but seems to work. But maybe we need to make 
that feature optional in future?

Another improvement would be to save VM state to absolute positions inside 
the state file. That way disk usage would be limited, and would use minimal 
space when file-system support sparse files. But this functionality would require
much more work inside qemu code. 

- Dietmar