If Vulkan API so cool , we can allocated all video memory GPU. For example 6 big allocations.
And then map first alloc. memory and save data to disk.
Then next.
And do it for all 6 allocations.
Its possible do ?
Basic examination of the Vulkan specification would tell you that not all memory you can allocate is mappable. You can copy it to mapped memory, but not all of it is mappable.
Equally importantly, you can’t allocate memory owned by another application; that would defeat the whole purpose of allocating memory at all. And there contents of memory you allocate are undefined.
Hm.
Vulkan API is not so cool 
Yes, Vulkan is so uncool that it prevents people from stealing your data.
And that assumes that the OS was going to allow you to break process isolation to begin with.
Well, there is the VK_NV_external_memory extension. How cool is that?
And saving memory to disk and getting it back later was never a problem. That’s just… standard thing to do.