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Re: Debian ISOs

Hello Anthony,

Thanks for the response.

On Thu August 31 2006 12:17, you wrote:
> Hi Bruce, just wanted to say thanks for investigating Metalink. These
> are all valid concerns. For the last few months, the only big user of
> Metalinks has been OpenOffice.org, and I haven't heard any complaints
> from mirror/server admins. That doesn't mean there aren't any. I'm
> sure there will be problems, and I'd like to work them out as soon as
> possible.
> Metalink allows for information on the country location ("location")
> of a server along with priority ("preference"):
> <url type="ftp"
>            location="au"
>            preference="30">
> ftp://mirror.pacific.net.au/OpenOffice/stable/2.0.3/OOo_2.0.3_LinuxIn
>tel_ins tall.tar.gz
>       </url>
> The simplest way might be for clients to try local mirrors, in order
> of preference, then all other mirrors in order of preference (or,
> other close countries). I think this added information of location
> and priority will lead to more efficient use of bandwidth over just
> plain links (hopefully).

I think you are correct, provided the clients prefer local mirrors and 
don't start casting around all over the 'net looking for a "great" 
server without good reason (whatever that may be. :-)

> Manuel has also made a web interface that generates Metalinks
> depending on what country you select.
> Metalinks can list multiple or single files.
> The size of Metalink files depends on how much information you want
> to include and how many mirrors are listed. For example, Metalinks
> listing every kernel.org or OOo mirror are around 20k. All mirrors
> for Fedora ISOs: 54k, Ubuntu ISOs: 58k, SUSE ISOs: 10k.


[quick manual counts, therefore approximate numbers]

Ubuntu has ~100 mirrors

Debian has ~36 primary + ~255 secondary mirrors

which indicates that a Metalink file for Debian could be over 150k;
(for CDs) x 12 (11 arches and source) x (>)15 images per release.
Giving ~9M of HDD overhead if each download needed its own Metalink 
file, <2M for one Metalink file per release, with reality somewhere in 

...so: HDD space shouldn't be a problem. It wouldn't be that simple 
though because Debian mirrors are not necessarily identical and Ubuntu 
appears to only have 3 or 4 arches with 3 images each on each mirror 
(iow, mirror count aside, more complex Metalinks would be needed.) How 
well the clients handle large numbers of <resources> is likely to be 
significant and could affect how many <resources> can be reasonably 
stuffed into a single Metalink; some of Debian's arches are rather 
limited wrt RAM and CPU cycles compared to modern standards, and 
Debian's minimum system requirements are low compared to others.

A scheme which is only useful to an arbitrary subset of Debian 
installations has less chance of being adopted than one which everyone 
can use. "Arbitrary" in that there may be no clear dividing line 
between `works' and `does not work' based on something other than the 
size of the Metalink file, the dependencies it drags in, available RAM, 
or other installation dependent variables (or whims). I'm not saying 
this is a problem with Metalinks, but it could be a problem unique to 
Debian and would need special attention.

> I'd be interested in working on any things that may be an issue for
> Debian as I'm sure they would affect others too.
> One thing I'd definitely like to do is get aria2
> (http://aria2.sourceforge.net/) included in Debian. It's a BitTorrent
> and Metalink command line client. Maybe recommending certain clients
> over another and working with the authors of those clients to be
> correctly coded and configured by default could help.


I'm not sure why it hasn't appeared in Unstable yet.
[but it looks like Patrick does :-]

- Bruce

p.s. - I'm not on debian-cd, CC me if you want.

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