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Enlighten me about jigdo ..


I wonder what this hype about jigdo is ..

What jigdo(lite) actually does(if I got it right ..):

1.get two files for an image - .jigdo, .template
2.download the listed files in the above two from a listed mirror using wget
3.run mkisofs to create the image

what I see at first glance:

1. the templates are BIG - as I see from 5 to 20 MB for woody
(600+ MBs for i386 sid, but I suppose the maintainer of those unofficial
templates has messed the things up, since this files are as big as an iso)
 I wonder what this binary data inside them is. What do they need
except relative file path, e.g. pool/main/a/aalib/aalib-bin_1.4p5-18_i386.deb
and possibly an md5sum for each file ..

2. Most of the mirrors probably provide http because http is an older
protocol. Jigdo docs says ftp is not efficient and http rocks. Ignoring
rsync precence(pipelining - no need to establish TCP connection for each file,
repair of broken downloads .. ) is a really bad idea

What is actually needed to achieve the jigdo features is:

1.use debmirror(over rsync!) to sync packages and files in let's say latest sid
2.use rsync to sync the md5sums with a master server so You won't have to search
  for a trusted mirror.
3.use mkisofs to burn your image. Note I currently can't find a way to achieve
  this last step. What is necessary here is to have a file with the layout
  of the debian cds to be supplied to mkisofs(or as an input to a script which
  creates the necessary directory structure) and an isoimage for the bootable cd.
  Probably some other minor details as cdlabels .. The cdlayout file is an ascii
  text file ofcourse and could also be rsynced. The jigdo-file(1) says you need 
  the iso image to create the .template and .jigdo files, so I suppose the 
  mentioned layout is actually used by the people making the iso-s ..

Having those three is enough to keep your system(probably server farm) uptodate.
What you do is just run debmirror to update to latest sid and upgrade the new packages.
You could always create the latest iso images too.

I'm either missing the coolest feature of jigdo, or proposing a more eficient
mirroring/iso creation scheme.

Anyone ?

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