Am 22.02.2013 um 12:21 hat Dietmar Maurer geschrieben: > > > For now I have no plans to backup such large VMs. > > > > 640k ought to be enough for anybody? > > > > Code is easy enough to change that "works for now" can be good enough. > > Changing file formats and external interfaces is hard, though, so better > > get it > > right the first time. I don't want to get patches for a new format in a > > year or two > > just because 128T was enough for the first few users. > > The limits are not really arbitrary - I choose them carefully to keep the > overhead small. > > We currently only need 8 bytes per cluster, which results in small files.
So how big is the metadata overhead? If you always copy 64k at once (which is a very conservative assumption - at least for the background copy you'll have much larger blocks), then an 8 byte header for each is 0.01%. Increasing that to 0.02% doesn't sound like a huge problem to me. And I think some other reasons were already suggested why using 16 bytes would be better, so maybe we should just do it. Kevin
