Here are some articles that are more for system management and maintenance.
- X11 VNC Server.
- Add a Maintenance LAN.
- Amanda Backup Server.
- Amanda Backup Client.
- Amanda Backup Usage.
- SNMP to manage and monitor the servers.
- Cacti to make graphs of your servers.
- Munin.to monitor and graph your servers.
- Nagios to monitor services and hosts.
- OSSEC intrusion detection and defense.