backup
Client backup new file  -> file,      gzip fd           yes
Server backup new file  -> fd,        file              yes
Server make sig         -> gzip file, gzip fd           yes
Client read sig         -> gzip fd                      yes
Client make delta       -> file,      gzip fd           yes
Server save delta       -> fd,        file              yes

backup finishup file
Server read delta       -> gzfile                       yes
Server make new file    -> gzip file, gzip file         yes

backup finishup
Server make rev sig     -> gzip file, file              yes
Server read rev sig     -> file                         yes
Server make rev delta   -> gzip file, gzip file         yes

restore
Server read rev delta   -> gzip file                    yes
Server make new revfile -> gzip file, file              yes
Server make new revfile -> file,      file              yes
Server restore file     -> file,      gzip fd           yes
Client restore file     -> gzip fd,   file              yes
