====Local mirror====
When installing a serious set of almost equal Debian or Ubuntu machines, it might be useful to create a local apt mirror. This has the advantage of saving bandwidth when installing more machines but more important, this gives the option to have 100% certaincy in doing reproducible upgrades on internal development, test and production systems.


===Apt-mirror===
Apt-mirror is a useful tool for this. It will allow you to select which parts of the apt software archive an official mirror (eg. etch, etch-security, for only amd64 etc) you want to mirror. This is useful because it allows a finer degree of control compared with plain rsync.

  apt-get install apt-mirror

Create an appropriate **/etc/apt/mirror.list** file. All repository lines which are normally in sources.list must be present in the file. And this has to be done for each separate architecture.

<code>
#set base_path      /var/spool/apt-mirror
set base_path      /export/www-root/repository-mirrors
#
# ## Mention: the base path and directories must be writable:
# set mirror_path  $base_path/mirror
# set skel_path    $base_path/skel
# set var_path     $base_path/var
#
# set cleanscript  $var_path/clean.sh
#
# set defaultarch amd64
#
set nthreads       2
set tilde          0
#
deb-i386     http://debian.slimdevices.com stable main
deb-amd64    http://debian.slimdevices.com stable main
deb-i386     http://debian.slimdevices.com testing main
#deb-amd64    http://debian.slimdevices.com testing main
#deb-i386     http://debian.slimdevices.com unstable main
#deb-amd64    http://debian.slimdevices.com unstable main
#
# set cleanscript $var_path/clean.sh
clean        http://debian.slimdevices.com
</code>


Create (or move) the three needed subdirectories: mirror, skel and var in the $base_path location (they are created in the application default location).


Showtime! Running the command below will start the mirroring process. It might be stopped during a run. When restarted, it will continue where is has ended. Remember, the ubuntu-7.10/debian-4.0 archive for only the i386 architecture is about 30GB big. 
  apt-mirror /etc/apt/mirror.list

Now link the directory in **base_path** to an apache (virtual)server and make the directory tree accessible with http. As a last step update **/etc/apt/sources.list** at all client machines.


===Debmirror===
Debmirror is another useful tool for this. It will allow you to select which parts of the apt software archive an official mirror (eg. etch, etch-security, for only amd64 etc) you want to mirror. This is useful because it allows a finer degree of control compared with plain rsync.
See: https://help.ubuntu.com/community/Debmirror


====Local Cache====
Better use apt-proxy (or apt-cacher for a large set of machines) when saving bandwidth is the only thing needed.