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Re: Conflict between Packages file and actual files

bmbuck@acsu.buffalo.edu (Buddha Buck)  wrote on 23.05.97 in <"btWcb1.0.S23.gCSXp"@debian>:

> > Dale Scheetz <dwarf@polaris.net> writes:
> >
> > > This is a continuous problem. I don't know why ftp.debian.org takes so
> > > long to get in sync with master, but the problem simply propogates from
> > > there to all the additional mirrors. Debian is the only distribution I
> > > know that depends so heavily on the accuracy of one file.
> >
> > This sounds like a locking problem to me.
> >
> > If the archive on master changes while the mirror to ftp.debian.org is
> > running, then the packages file will obviously differ from the
> > contents of the archive. This can continue down the chain of
> > mirrors.
> >
> > Assuming no locking takes place, then differences become increasingly
> > likely as the time taken to update the mirror increases. Another
> > source of this is if the packages file on master is not updated
> > immediately after a package is added. These problems will presumably
> > settle if the archive is unchanged for a couple of days.
> I think its a combination of these two.  I think that the archive on
> master being updated asynchronously with the package file is a problem
> (it leads to an inconsistant archive, for one thing), and I think that
> ftp.debian.org mirroring without locking is a problem.

ISTR that what actually happens on master is:

* At the beginning of the regular archive maintenance, a flag file is  
created (Archive.Maintenance.In.Progress or some such name).

* At the end, the file is removed again.

* A time of day is defined when the regular maintenance takes place, so  
mirror runs can be scheduled to avoid it.

This leaves manual maintenance. I don't know how this is usually handled;  
but it doesn't happen very often.

Frankly, I don't understand _why_ ftp.debian.org has these problems.  
Either they have a _really_ bad connection to master, or they may be doing  
something wrong.

> If this could be automated and run at a set time, then "locking" could
> be achieved by scheduling it at a time when ftp.debian.org -won't- be
> mirroring it.  That way, ftp.debian.org is maintained as consistant.
> Similarly, if the mirroring could be achieved in the same order (new
> files, Packages, delete old files), then even during mirrors,
> ftp.debian.org would be consistant.

This schould already be happening, as a result of the above scheme. Except  
for the manual maintenance, everything should be automated ans scheduled  
to get it right.

If this doesn't work (and it sure looks that way), there is a bug  
somewhere, not a design problem. We need to find that bug.

Hmm. Some thing that might help is a regular automatic comparision of  
ftp.debian.org and master.debian.org. I'll think about that for a while  

MfG Kai

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