Zwei parallele Server

yes i konow, but Tell me the meaning, to use an Old Stable.... Jessie commes to Featurefreeze in Nov sooooo, why not update to latest Stable

because of the risk at updating distro. ofc, i would not suggest to install squeeze on a new setup, but updating a distro in a running server environment is risky
BTT: always do a backup and test every update on a testing machine