On 7/14/07, Anil Gulecha <anil.verve at gmail.com> wrote:
> Hmm..
>
> I think that BeleniX iso is non-ISO compliant, due to the files on it
> being arranged. That si alright. As far as checking the consistency of
> the CD, md5 digest should be the correct way to check. If you download
> the file by torrent, then the built in hash checking is good ehough to
> download only the incorrect pieces.

Hi Anil, I'm not sure what you mean about the ISO, but it's still a
file. Yes, you can manually verify the full file checksum, and yes,
you can repair a corrupted download with a torrent, but because of
restrictions and configuration issues, not everyone everywhere can use
a torrent. With a metalink, the download can be repaired from FTP/HTTP
resources, with no torrent needed (altho some clients can combine
them).

> The metalink XML for belenix is quite interesting.  Apart from the
> regular checksums, the image is divided into 86 chunks with individual
> checksums.  A compliant FTP client should be able to repair the ISO
> image by just re-downloading the corrupt bits - much like bittorrent.

Hello, Venky. That's exactly how it works! It's all pretty simple,
once you look at the XML like you've done it usually makes sense. I
don't always go into it, but try to explain it with "error correcting"
or "self repairing/healing" or other phrases that don't always get the
point across. And yes, it works over FTP/HTTP. It can also be very
fast if a file is on multiple mirrors (like the OpenOffice.org or
openSUSE metalinks). Give aria2 a try if you have time.

> Anthony,
> Is there a way to configure the number of chunk the ISO is divided into?

Yes. I assume you would want more chunks, so if there were errors, the
re-downloaded chunks would be smaller? That would be better on error
prone connections, but slightly increases the metalink file size
(50-100k, not really an issue when downloading a 700 meg ISO :) Let me
know, and I will redo the .metalink.

-- 
(( Anthony Bryan ... Metalink [ http://www.metalinker.org ]
  )) Easier, More Reliable, Self Healing Downloads

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