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Re: Debian ISOs

On Wed August 30 2006 02:52, Subredu Manuel wrote:
> Josselin Mouette wrote:
> > Le jeudi 17 août 2006 à 11:48 -0400, Anthony L. Bryan a écrit :
> >
> > Given that downloads like Debian ISOs are already putting a heavy
> > bandwidth load on the servers and that they are already shared
> > among many servers, I don't think it is a good idea to encourage
> > users to load several servers at once with one download. We should
> > instead push bittorrent as the main distribution media for ISOs.
>  I don't think you got the picture. Metalink can contain information
> for download using the following protocols:
>  *) http
>  *) ftp
>  *) bittorrent
>  *) e2k

You seem to be ignoring that metalinker will use multiple protocols, 
servers, and connections in an effort to get the fastest download. 
http://www.metalinker.org/Metalink_3.0_Spec.pdf also indicates it will 
switch servers if the download rate falls, and perhaps even perpetuate 
old torrents --- which is all great for the client, but will pretty 
much guarantee worse than possible performance from the servers.

It is also not clear what will happen when a release is made and 
hundreds (thousands?) of clients hit the fastest mirror, whose download 
rate then drops, prompting all the clients to try switching to the new 
fastest mirror, whose rate then drops, ...  At the very least there 
will be more overhead traffic for the servers, worst case could be some 
kind of nasty cyclic oscillations with the server loads which 
undermines transfer efficiency for everyone.  Ya, that's kinda FUDish, 
but given the newness and limited deployment of the technology, 
speculation is about all we have to work with.

The objective is to ease and spread out the load on the servers; 
bittorrent and socially engineered access to the less efficient 
protocols is more likely to do that than bittorrent + ftp + http + 
multiple servers/client. IMO

I think Metalinks are an interesting idea which deserve investigation, 
but it seems clear they would result in more server overhead and 
unclear whether the load spreading would offset that or even happen[1].

- Bruce

[1] could clients be attracted to a few fast ftp servers and the often 
slow-to-start torrents end up being underutilized... the exact opposite 
of what is best for Debian's servers.

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