On 05/01/12 19:44, Paul Stauffer wrote:
> On Thu, Jan 05, 2012 at 01:29:48PM -0600, Adam Miller wrote:
>> On Thu, Jan 05, 2012 at 01:15:15PM -0600, Ken Teh wrote:
>>> Quick question?
>>>
>>> I needed some packages from epel so I added the epel rpms from SL6x.  Is
>>> it okay to leave the yum.repos.d/epel.repo enabled?  Are there packages
>>> on epel that will clobber the SL6x packages during the nightly updates?
>>>
>>> Thanks!
>> The policy on EPEL packages and updates are to not clobber anything
>> shipped by Red Hat in RHEL proper (including the optional channels in RHN)
>> so pending what all from RHEL is put together to make SL I would imagine
>> its quite safe. I personally run EPEL on my RHEL, SL, and CentOS machines
>> and to date have not run into a package clobber issue (though I have a
>> number of times with third party repos that aren't EPEL). That is not to
>> say it won't ever happen, but I've never personally found an instance in
>> which it did and the EPEL folks do make an effort to keep it from
>> happening. I personally think its pretty safe, but YMMV.
>>
>> -AdamM
> I would second Adam's comments.  Plus, if you are installing some packages
> from EPEL, you will probably want to leave it enabled so that those packages
> are kept up to date as well.
>
> If you want to verify the effects of enabling EPEL (or any other 3rd party
> repo, for that matter), just enable it, and then manually run "yum update".
> It will print out the list of updates it proposes to apply, along with the
> repo each package is from.  You can read through the list to see if it looks
> like anything from the 3rd party repo is going to update a package from the
> core repos, and if you're not comfortable with anything, just answer "N" to
> the prompt and disable the repo again.
>
> cheers,
> - Paul
>

Using EPEL is generally safe, specially if it's the only 3rd party repo 
you're using. However, together with Atrpms or RpmForge, there might be 
some issues with package version differing from EPEL and the other 
repos. One example is when installing vlc from RpmForge, which pulls the 
libmodplug and libudev libraries from EPEL (more recent) although it 
requires RpmForge's one.

Best pratice is:
1) set priorities or protectbase up to avoid 3rd party repos being able 
to override your RH/Centos/SL base installation,
2) enabling one 3rd party repo at a time and perform the installation of 
the wanted package,
3) if a conflict occurs, identify the problematic packages and resolve 
the conflict (usually using the exclude option in yum repository config 
files)
4) once your system is set up, 3rd party repos should be disabled. 
Although, opinions are mixed about whether to keep the repos enabled or 
not, my personal experience dictates me not to do so.

Hope this helps. This CentOS wiki article can help: 
http://wiki.centos.org/AdditionalResources/Repositories

Ghis