> > > We track zero regions at 4K level, and Cluster size is 64K. > > > > > > So I normally just use 1bit to store information about empty blocks. > > > > > > I thought that is quite good, but you obviously have a better idea? > > > > Maybe I didn't understand right then. These zero regions are just for > > describing empty sectors within non-empty clusters? > > I currently also write an entry for empty sectors. But this is only done as > additional error check, to prove that the backup tool wrote all data.
BTW, this can be also useful when you have a damaged backup file. The extend header contains checksum and special markers. All that info together let you know what blocks are missing (exactly).
