[Mageia-dev] Mirror layout, round two

andre999 andr55 at laposte.net
Fri Dec 3 06:07:27 CET 2010


Maarten Vanraes a écrit :
>
> Op donderdag 02 december 2010 08:20:15 schreef andre999:
>> Maarten Vanraes a écrit :
>>> Op woensdag 01 december 2010 21:54:48 schreef andre999:
>>> [...]
>>
>>> i also see that mirror layout should be as easy as possible for mirror
>>> admins.
>>
>> Agreed.  However keeping an extra set of repositories for core packages
>> would just add a few extra directories (without changing the number/size
>> of their total content), thus have little impact on mirror administration.
>
> One would think so; however, a few people who replied where mirror
> administrators; and it seems, IIUC that they said it does have impact.
>
> I'm just gonna trust their judgement on this, since they know more about this
> than myself.

Mageia requires mirror sites to use rsync for mirroring.
Mirroring at least every few hours, if I remember correctly.  (I forget 
the other details.)

They need a single line of code, something like

rsync -ra {URL-source-directory} {local-destination-directory}

This is very easy to do : Mageia gives the source URL (and the options 
required), and the mirror site knows the destination directory.

This line of code is put in a cron (or acron) job file, configured to 
run automatically at the specified regular intervals.

If they exclude the optional "tainted" repositories, they have to add an 
"--exclude" option with the relative path to these repositories.
(Still in a single line.)
Fairly straight-forward.

Why system admins in multi-mirror sites with lots of other tasks would 
like to avoid optional repositories is that they are probably already 
overloaded with things to do, and adding the exclusion multiplies the 
risk of having a (tiny) error that makes it not work.
Also, a minor change at the Mageia source could make it stop working.
The last thing they need is another problem.

> [...]
>>
>> Note that if, down the road, we find another effective method for
>> distinquishing core / non-core, it is relatively simple to transfer
>> packages in "extra" to "core".
>> But if we eliminate the parallel set of repositories, and find later
>> that we have a problem giving priority to core packages, moving in the
>> other direction would be a much more difficult process.
>
> IIRC someone with experience said in this thread that we could always go to
> that sort of scenario if like this it wouldn't work well. Again, i'm gonna
> trust their judgement on this.

( At least some things said in this thread seem to me more in the line 
of wishful thinking.  A bit like "I'm not planning to have an accident, 
so why do I need a seat belt ?" )

I still think it would be better to later remove than add.
The main problem is that without the separation by repositories, in 
order to ensure full support for core modules, we would need another 
control.
If we start with separate sets of repositories, that control is already 
there - removing the complication of adding some other control in 
setting up the system.
Maybe we can find a way of setting up a reliable such control in the 
build system without a too much effort.  But it is more effort, subject 
to debugging, etc, as with any new code.

regards

- André


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