Knoppix download & Jigdo

[marquentein]

First of all I would like to thank Klaus Knopper allot for maintaining the Knoppix distro. It has proved immensly usefull to me in various situations when I wanted something up and running and time & ease was a major factor aka. demonstrating Linux, recovery from a WinBox, quick-install Linux etc.

I admit that I download a fresh copy of Knoppix every time a new version is released. With the introduction of the DVD version I began to wonder on my contribution to the stressload on the download mirrors and the increased risk of broken/interrupted downloads etc.

Since Knoppix is a Debian deriviate and Debian already use Jigdo as a means of ISO download to forsee the above mentioned issues I was wondering:

What is the official opinion of putting up Jigdo mirrors of Knoppix?
In case the idea of using Jigdo is positive would it then be something that is likely to be implemented?

In respect to previous postings on this forum alternatives have been mentioned: BitTorrent and Rsync

BitTorrent is not an alternative to me due to firewall issues as well as in-house ISP EULA which prohibits usage of P2P.

I am not very familiar with Rsync but I wonder if it supports broken downloads? In any case it is my belief that Rsync is not able to reuse unaltered/nonupgraded files from a previous Knoppix CD/DVDs and thus save bandwith as is the case with Jigdo which is why I for now vote "Jigdo" in favor of "Rsync"

Besides Jigdo operates on top of HTTP/FTP and thus doesn't require any new technology installed at mirror server end.

Just like BitTorrent then Jigdo also use a central MD5SUM-file to verify that your downloaded files match EXACTLY the intended ISO-file put up for download meaning that Jigdo downloads can't be tampered with.

[cvevans]

I want to second this suggestion.
Since 5.0.1 came out with old insecure Firefox 1.5.0.3,
we need an update - at least for security only - ASAP!
BUT I would like to NOT redownload the 99% that did NOT change!
Jigdo would be ideal!
For the DVD, it would be more like 99.8% unchanged.

I would like to see also ability to add a track to the DVD for updates,
since the DVD is not full yet (UnionFS the 2 tracks?)
Until then, Jigdo solves the problem.

[DirkS]

I am not very familiar with Rsync but I wonder if it supports broken downloads? In any case it is my belief that Rsync is not able to reuse unaltered/nonupgraded files from a previous Knoppix CD/DVDs and thus save bandwith as is the case with Jigdo which is why I for now vote "Jigdo" in favor of "Rsync"

Rsync considers a file as "stream of blocks", similar to bittorrent, and should be able to update parts of a file. So, yes, it can deal with interrupted/broken downloads, at least theoretically. The problem is that the biggest part of the image is compressed and a change at a certain part may change all following blocks.

Besides Jigdo operates on top of HTTP/FTP and thus doesn't require any new technology installed at mirror server end.

That's IMHO the best pro-argument for Jigdo. And yes, I second the idea! But - to make good use of it, it might be nneded to uncompress the KNOPPIX image first, do the update, then re-compress it.

Just like BitTorrent then Jigdo also use a central MD5SUM-file to verify that your downloaded files match EXACTLY the intended ISO-file put up for download meaning that Jigdo downloads can't be tampered with.

Usually, rsync creates checksums for blocks on the fly, giving you the same protection - or even better, because you could use a broken file as basis and rsync will download the different parts and merge them in.

Alas, I never tried to use rsync for updating knoppix. I cannot because of firewall issues.

Regards
Dirk