Modern Update System

[David Woodhouse]

On Tue, 2005-11-29 at 16:01 +0000, Nigel Metheringham wrote:
> How well does it work if you pull the rpm header (presumably thats
> always needed for an update), build the payload using existing files on
> the system (ie from the previous install) via cpio/minigzip, glue the 2
> together and rsync that?

Badly. The compressed payload doesn't rsync well -- you have to
decompress it if you want rsync to do anything other than just download
it all again.

There were once some zlib patches which made zlib-compressed stuff
slightly more rsync-friendly by deliberately discarding history and
inserting sync points in the data stream, but they're not a patch on
just rsyncing the _uncompressed_ version.

> It does require mirrors to give rsync access - which is probably
> pretty wide spread *but* would need the rsync URLs for mirrors to be
> made available - you can't just assume that you can do 
> s/^(f|ht)tp:/rsync:/

Yeah. Even rsync access to the extracted cpio payload shouldn't be
entirely impossible.

-- 
dwmw2