Re: www.debian.org very slow indeed?
On Sun, 9 Jan 2000, Carl Fink wrote:
> Has anyone else noticed that the main (US) Debian servers have been
> remarkably slow lately? Both trying to use the web site, and
> ftp.debian.org for apt.
>
> I've switched apt to a mirror, but the mirrors of the web site are
> also so slow as to be nearly unusable?
One problem is the mirrors themselves. There is no standard method for
mirroring or any policy. I often hit mirrors that appear to be in the
process of upgrading ... archive is missing a file that the packages file
contains. You never know which mirror you will get when you use
http.<country>.debian.org and when you do an update you get a packages
file from one site and when you do the upgrade you might go to a different
site that may not match the packages file that you got from the other
because of the round-robin DNS.
In other words:
nslookup http.us.debian.org
Addresses: 63.209.15.252, 207.69.194.216, 24.220.0.13, 209.249.97.234
141.213.4.21
Ok, so now I do
apt-get update
and I connect to 63.209.15.252
Then I do an
apt-get upgrade
and start pulling files from 207.69.194.216
There is no policy for ensuring that the Packages file on 63.209.15.252
matches the files on 207.69.194.216 so failures are frequent. To avoid the
whole problem many just use ftp.debian.org and are done with it. I really
do not care if things are not the most current, I do care that it is
consistant and predictable.
Hate to bitch without offering a suggestion so one way of doing this is:
1. round-robin mirrors grab all the new packages
2. they notify the central server that the update is complete
3. Once all servers have notified the central server that they have all
packages, the new Packages files are pushed to them and old packages
that have been replaced (files that no longer exists on the master )
are deleted.
4. If a server has not notified the central master by a certain "drop
dead" time, it is removed from round-robin DNS and the Packages files
are pushed to the others. Once it reports in, its Packages file is sent
and it is added to the round-robin DNS.
This ensures that the state of all the mirros remains consistant even
while they are updating since the Packages file does not change on ALL of
the servers until they ALL update (or until a certain time). People
downloading old files while new ones are being retrieved are OK because
they have not been deleted yet.
Heck, just doing 1-3 above is an improvement.
Get new packages (excluding Packages files).
Get Packages files.
Do deletes.
4 just makes sure that all the archives are in sync so if you update from
one and upgrade from another, it works.
The major problems are that Packages files are obtained at aome arbitrary
point in the mirroring process so it does not reflect the state of its OWN
archive and the mirrors are not in sync so the state of one is not
reflective of the state of the others.
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