After purchasing two dell 720 machines for a project at work, I went around setting the machines up in a very basic Pacemaker cluster. Just one problem the network interface between the machines (crossover cable) would shut itself down. But the connection to the switches would be fine. The only way to get it going again was a ifdowm amd ifup, after scratching my head and looking through the device driver.
If you remove a package from a debian package and for get to add the -purge argument the package will leave its configurations files on your system. In order to view all the packages that have done this you can simply run. sudo dpkg -l | egrep "^rc"` If you wish remove those configurations files you can simple run sudo aptitude purge ~c