[BitTorrent] Bittorrent as a large-scale software distribution system

Harold Feit - Depthstrike.com Administrator dwknight at depthstrike.com
Tue Jun 8 13:39:23 EDT 2004

Alright, about using BT as an alternative to FTP mirroring.

If you mean using special clients as alternative trackers, you're probably
looking into something that isn't necessary. Even at 10k peers, a typical
business-level webserver can handle the load without even flinching.

Piece sizes are pretty easy to handle. Even at a piece sizes varying from
between 256k and 2m I was able to maintain upstream of about 1.5mbyte/sec on
a laptop uploading to a desktop over a 100mbit lan in a controlled

BitTorrent's transfer rate potential (I say potential because I know that
real life doesn't work that way) grows exponentially as the swarm grows with
each client becoming a partial mirror as it gets new pieces.

Using BitTornado and its variants are how I tested the transfer rates. Using
Super-Seed mode from those clients during initial uploading will increase
the overall speed of the swarm greatly since rarest pieces are sent out
first, generating new seeds as early as uploading 550mbyte for a 500mbyte
file in my test environments.

A 100mbit BT seed with 10 simultaneous uploads can generate higher overall
transfer speeds as compared to a 100mbit FTP server with 10 connections
(properly configured and uploading to the same initial downloader base).

-----Original Message-----
From: Francois Petillon [mailto:fantec at proxad.net]
Sent: Tuesday, June 08, 2004 12:09 PM
To: BitTorrent at yahoogroups.com
Subject: Re: [BitTorrent] Bittorrent as a large-scale software distribution

Jesus Cea Avion wrote:
> I was thinking about limiten that knowledge to the peers in "mirror"
> sites. The idea is that each "mirror" site serves only "near" peers.
> Usual clients are not affected in any way.

OK, here is my .50 $ about "large-scale distribution system". :-)
I am managing a ftp mirror (ftp.proxad.net) which do not have load
problems excepted when a new popular linux distrib is released (over 700
Mbps here for two days for the lastest Mandrake release). Main problem
with ftp is related to being able to easily add a small temporary server
with most requested contents (ISOs...) I may cheat by using caching or
proxiing frontals (but it would mean they have to manage all network
traffic which, IMHO, is not a good solution).

FTP mirror is quite nice as you select the content you want to mirror
(but BitTorrent should act the same) but your need in storage are quite
big and it is difficult to temporary scale.

I do not know if BitTorent may be the answer but, if I understood well
BT architecture, seeds would need to know when they have "special
clients" (I limit ftp slots depending on local/peering/transit IPs and
it works nicely here) but, with BT2, they also could use these "clients"
as specific backup trackers. BT drawbacks are probably related to max
chunk size (on I/O loaded server, you try to read the biggest block size
possible). On the pro, it should be quite easy to partially mirror a
content and to limit this mirror size depending on disk space available
("regular" server) or on the RAM size (to keep only a few very
frequently requested contents and use this server to offload your main

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