On Sat, Aug 20, 2011 at 11:36:58AM -0400, Joey Hess wrote: > Julian Andres Klode wrote: > > The problem is that future changes might change the format in ways that > > can still be read by older xz versions, but are not byte identical with > > them. This is one thing that makes it hard to have an --rsyncable option > > in xz [1] and probably also makes it complicated to support for > > pristine-tar. > > This could happen with gzip too (in fact, it recently *did* happen with > gzip --rsyncable). This can be dealt with if it doesn't happen too often > by embedding the old version. I don't know how often it happens, but I guess more often than for gzip or bzip2.
> > You'll be able to use tarballs from gnome.org once gnome.org starts with > > shipping only .xz tarballs [2]. > > This will be a sorta large corpus, but probably not a very diverse one. Maybe. Just for the record: xz currently has 20 levels of compression, namely -0 ... -9, and -0 ... -9 combined with --extreme. Varied are dictionary sizes and an other LZMA2 option or so. Future versions will have multi- threaded compression which might then produce even more randomish files. Then there is also different block sizes, and the ability to specify a memory limit for compression which changes settings accordingly to fit into memory. -- Julian Andres Klode - Debian Developer, Ubuntu Member See http://wiki.debian.org/JulianAndresKlode and http://jak-linux.org/.
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