[Mageia-dev] Proposal for Mageia: implement bitorrent protocol to allow updates download

Olivier Thauvin nanardon at nanardon.zarb.org
Wed Jan 12 17:07:15 CET 2011

* andre999 (andr55 at laposte.net) wrote:
> Olivier Thauvin a écrit :
>> * andre999 (andr55 at laposte.net) wrote:
>>> Michael Scherer a écrit :
>> This is a selfish point of view, nothing is important except the result
>> on your side.
> Sorry, but this can't be serious.
> If a user is to download say a 4,7G DVD iso, it is 4,7G if the user uses  
> one or 5 connexions, from one or 5 mirrors.
> And if the 5 connexions go to 5 different mirrors, that is only 20% per  
> mirror.
> Globally, if the same files are downloaded, the same amount of data is  
> downloaded.
> What we are talking about here, from the user side, is downloading  
> faster, if the capacity is _available_ on the network of mirrors.

Exactly, it is seriously a selfish point of view as:
- you're talking about users side, me both
- IF the capacity, obviously no one really know the capacity of mirrors
  except admin of them (and I am one of them).

Moreover you're mixing "downloading on several server" and "downloading
several time on one or more servers".

> There are many mirrors which provide multiple connexions, with a very  
> large bandwidth.  If users don't use the available connexions on these  
> servers, other mirrors will be more heavily impacted.
> So, as I said in another post on this thread, it is win-win for both  
> users and mirrors.

All mirrors provides multiple connection, otherwise they would serve
only one client a time...

And no, it is not win-win, I am trying to explain, munin statistics in
hand, only the users think to win something. And you're ignoring my
comment as mirror admin.

> Think of it another way.
> Scenerio 1)  Suppose at this moment the mirror network has 20% free  
> capacity.  We download without multiple connections or multiple mirrors,  
> without using this excess capacity.  In one hour we are still  
> downloading, at a time when there is no free capacity.
> Scenerio 2) We download using multiple connexions and multiple mirrors,  
> accelerating the downloads with the otherwise unused 20% free capacity.  
> In one hour, most of our downloads are finished, thus leaving free  
> capacity.
> Just who is served by scenerio 1 ?

Mirrors, they are not serving only you and your 5 connections, they
already serving 100 users other than just you !

I cannot see how the mirror will give more bandwidth with 1 or 5
connections. Except in the case each connection take same amount of
bandwidth, then you're 5 part while other take one. And this is not a
fair use of ressource.

> The users that don't have access, or the mirrors that are overloaded ?
>> Of course, if in the case I don't blacklist mageia and deny download via
>> http/ftp to save my mirror (d-c is already under heavy load).
>> So, no, don't donwload several times from a mirror.
> The solution ?  If a mirror can't handle multiple connexions, restrict  
> it in some way.  Many mirrors do.  Either all the time, or from time to  
> time.  Or throttle the transfer speed.
> Just do whatever works best for the mirror in question.
> However let users use the capacity available.  Because it may not be  
> available in one hour, or even 5 minutes.

The problem is (maybe I am not clear) your 5 connections will get queue
letting other people having to wait more to download their file, or
getting "too many connections" error.

Indeed, this maybe does not matter for you, except when you'll complain
because the distribution cannot be download.

> Why not think globally ?

I do, especially, I prefectly when http stop to reply, it stop to reply
globally, for Mageia but also for Fedora / Ubuntu / Scientific Linux /
Arklinux / Gentoo / ... and all other project hosted on mirrors.

This is really a more global issue.

I also think my mirror have first to serve my work, and time to time
my colleague complain about slowdown cause by external downloader (eg

Here my POV:
1) I am mirror admin and get tired of abuse
2) I am mirror manager for the distro

a) According the fact doing this create an huge load on some mirrors,
b) according we'll have to search mirror around the world and the distrib
  size is already a problem
c) according doing this can discourage people offering space and bandwidth
  for us

I am aginst such things.

I cannot deny you to do this, but don't complain if no mirror agree to
serve you.


Olivier Thauvin
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