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Re: jigdo for debian-live images ? (was: Debian mirrors: ftp.coe.psu.ac.th)

On 2009-09-27 Simon Paillard wrote:
> Hi debian-live,
> In short: what is the similar (and easy) wat to build images as jigdo
> does ?
> On Sat, Sep 26, 2009 at 12:08:23PM +0700, Chatchai Jantaraprim wrote:
> > On Fri, Sep 25, 2009 at 07:13:56PM +0200, Simon Paillard wrote:
> > > well use jigdo to build the images locally instead of wasting
> > > bandwidth, see http://www.debian.org/CD/mirroring/#jigdomirror
> >
> > 	Yes, I try to figure out how to use jigdo to create iso files locally.
> > 	From the first few attemts it seemed not too difficult to do so.
> > 	Just mirror only .jigdo and .template, checksum those files using md5
> > 	and create those isos if necessary.
> >
> > 	But I'm not sure how can I create those live-cd/live-usb image.
> > 	Is there any templates that I can use with debian-live and
> > 	create the images for our local mirror.
> Very good question, followed-up to debian-live.

Can you explain more about the reason(s) to use jigdo to update the live-images?

I think that jigdo is (far) less suited to updating live-images then it is to installer-images, 
since installer-images contain a lot less and bigger files, namely a bunch of .deb files, then a live-
images does.
A live-image is basically a normal (debian) system, which consists of a whole bunch of small(er) 
files, but compressed + some files to set it up.
I've recently build a live image myself (sid, kde4.3.1) which is 534MB in size, but when I extract 
that it turns into 60839 files and 6976 folders.
So when you want to update that with jigdo it'll have to check 60839 files and update all the 
different once.
My experience with jigdo* learns me that connecting to the server to retrieve a file takes by far the 
most time, the download itself is quite swift. With soo many files, that can take quite a while (to 
update a couple of MBs?).

On the other hand, bittorrent seems quite appropriate for this and I wouldn't mind that being 
stimulated more. It gives the users speedy (most of the time) downloads, while it doesn't drain on 
debian's bandwidth. 
I'm currently seeding debian-live-kde_4.3.0-i386.iso (via http://pkg-
kde.alioth.debian.org/kde4livecd.html), but it's a 'shame' that in the trackers I only find 
torrentbox.com and thepiratebay.org and not debian.org.
And if Debian Live is meant to make official debian live-images, it would help if it gets a more 
prominent place so that ppl can find (and use) it more.

And to answer your original question:
You need to unpack the iso, extract the squash file system from it and unpack that, remove the squash 
file system file, update the files from the squashfs file and pack that up again and construct the iso 
with the updated squashfs file.
is a good place to start and with method 1, 'replace' the chroot steps with the jigdo updates.


* When a new stable DVD images comes available, I'll update it with jigdo feeding it my .iso/DVD and 
let it generate a new .iso file and then I download the .torrent file and point that to the existing 
.iso file, so it'll check it and starts seeding since it's already fully up-to-date.

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