> > > We track zero blocks at 4KB level to get small backup files. Restore > > > can handle those blocks differently, either pre-allocate or create > > > holes. That > > can even be a restore option. > > > > You are right, the behavior can be set at restore time. > > > > I'm curious how much of a win the 4 KB zero detection is on random > > Linux or Windows guest images. Have you collected numbers? > > Well, seems that it does not help much - it saves about 0.2% space. So maybe > we can remove that feature (and increase address space in the VMA format > instead).
Sorry, I need to correct myself - I had a bug in the code. I can see space reduction up to 4% using this feature. Considering the fact that it comes at no cost, it would be stupid to remove it.
