On 23/02/13 21:36, Mahmood Naderan wrote:
> Hi
> I have noticed that sometimes when I run "yum install" or "yum list", it
> wants to update the repository 
> [root@localhost trunk]# yum install glibc-static.x86_64
> Loaded plugins: fastestmirror, refresh-packagekit, security
> Loading mirror speeds from cached hostfile
>  * epel: ftp.riken.jp
>  * sl: ftp.scientificlinux.org
>  * sl-security: ftp.scientificlinux.org
> epel/primary_db                               21%
> [=======-                           ] 65.0 kB/s | 1.1 MB     00:10 ETA
> 
> However for some other "list" and "install" commands, there is no
> repository update.
> 
> What is the reason for that? Maybe because it "epel" and has not been
> shipped with the default SL.

It really dosn't have much to do with being shipped with SL or not.
This is quite normal.  Yum will always check all enabled repositories
when doing searches/queries, installs, upgrades or downgrades.  And each
of these repositories may have different cache expiry timestamps.

That is: yum will cache the remote repository information for a while,
to avoid downloading this information each time you do a yum operation.
 And when yum figures the cache has expired, it downloads a new one.
This can also happen with the SL repos as well.

And you can expire the yum cache at will too, by doing

   # yum clean expire-cache

This will cause yum to download all repos again on the next yum operation.



kind regards,

David Sommerseth