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

Olivier Thauvin nanardon at nanardon.zarb.org
Wed Jan 12 12:52:32 CET 2011


* andre999 (andr55 at laposte.net) wrote:
> Romain d'Alverny a écrit :
>>
>> On Wed, Jan 12, 2011 at 04:29, Michael Scherer<misc at zarb.org>  wrote:
>>
>> However, if 1) was to open 5 connections on 5 distinct servers, that
>> would make more sense, no?
>
> Right.
> Another way to look at the question :
> If 1000 people are downloading from mirrors allowing a total of 2000  
> connexions, if no-one uses multiple connexions, then 1000 connexions are  
> wasted.  These unused connexions would likely be from faster mirrors.

The upload given by a serveur is split in term of:
- connection available
- bandwidth available.

If the mirrors is connected to Gb (which is more likelly the size of
bandwidth for the whole university...), and you split this Gb/s onto
2000 connection you obtain 500kb/s.

However, I know only few server in the world really able to read Gb/s
from their disk. The top rate I obtain on dc is 400mbis/s (the memory
cache help a lot to obtain more).

The number of connection is set high because some people download at
only 50kb/s and other 2Mbit/s, so the spare bandwidth from the 50kb/s
can be given to others. Nothing more.

According the graph on distrib-coffee:
http://distrib-coffee.ipsl.jussieu.fr/munin/distrib-coffee/distrib-coffee/index.html
there is an average of 100 http download at a time, if each connection
become 5 (500), you'll reach the limit (200 on this server).
What will be the gain on your side ?

I talked here only about http, but apply the same to ftp in the same
internet connection, so it mean I have 100mbits/s to share between 400
connections.

As Mickael explain, I voluntary limit the count of connection per IP,
before I did this, the server was overload 12 hour a day, which mean
stop serving !

> With aria2c, 3 mirrors which support a total of 5 connexions gives me  
> optimal speed.  (The limit being the speed of my computer.)

Can we know the speed of your connection ?

Maybe your connection is good enough to provide a mirror for Mageia ?
And then you'll be able to test what you're suggesting.

What is the result with 5 mirrors and 1 connection per mirror ?

Obviously, any mirror in France (I am in France) is able to fulfill
my personnal connection... (10mbits/s).

-- 

Olivier Thauvin
CNRS  -  LATMOS
♖ ♘ ♗ ♕ ♔ ♗ ♘ ♖
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