> > > Maybe you'd better use a different output format that doesn't > > > restrict you to 64k writes. > > > > The output format is not really the restriction. The problem is that > > an additional IPC layer add overhead, an d I do not want that (because it is > totally unnecessary). > > I missed the reason why you cannot increase the block size.
When we run backup, we need to read such block on every write from the guest. So if we increase block size we get additional delays.
