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Re: ftp1.us.debian.org and FTP mirrors



On Thu, Oct 22, 1998 at 09:58:33AM -0500, servis@purdue.edu wrote:

> | Look at my netselect package, which chooses the "fastest" server from an
> | arbitrary set of supplied names.  I designed it exactly for this.  Version
> | 0.2 actually works.  It merely needs to be integrated into APT somehow...
> | 
> 
> Without looking at the package and how it works I want to make a few
> comments.  I think this whole idea of choosing a mirror that is close
> and fast is a great idea.  However the code must take into account that
> a majority of people may not have dedicated net connections, real dns
> host names or even be connected when they install.

Thanks to Jules, I think he answered this nicely...

> One approach would be to use the timezone information to pick an
> appropriate mirror. Of course the timezone of the mirror would have to be
> stored in the mirror info.

It's a _totally_ ugly myth that geography has anything to do with net
performance.  In Canada, for example, almost everything goes through the
U.S. at some point because they have a more complete/redundant/fast Internet
backbone than we do.  That means that although I'm in Waterloo, Ontario,
talking to a server in Toronto (an hour away by car) can often be a _lot_
slower than one in Seattle (far away).

And some net links are really loaded down -- ftp.de.debian.org is faster for
me than some U.S. sites.  I realize that using transatlantic links for
this stuff is wasteful... luckily most U.S. sites are faster for me than
Germany is :)

Furthermore, with a cable modem, it becomes increasingly important (and
difficult) to find the "fastest" server.  The difference between 20k/sec and
200k/sec is a big one.

Netselect takes all this into account, using a heuristic based on the number
of hops, packet loss, and average ping times.  It does several things at
once so it can go through a long list of servers in a short time.

> Wasn't Jason working on a new Package file format for the mirror list. 

I think so.  Last I checked, it was missing a lot of mirrors including two
of the fastest for me (ftp.cdrom.com and debian.crosslink.net).  As far as I
know, there's also no useful conversion script for it yet... (to make it
into a sources.list file after passing it through netselect).

Have fun,

Avery


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