• Fault Tolerance / Redundancy -- what level of redundancy and/or error detection is required to meet SLA, identify single-point of failures and quantify risk
• Capacity -- servers and services
  • Maximum load
  • peak load
  • average load
• Security -- multiple networks, secured ports, firewalls, administrative procedures
• Scalability -- mid-term and long-term considerations; identify and quantify thresholds requiring physical upgrades, identify and quantify absolute maximums
• Maintainability -- identify and quantify necessary maintenance windows and/or design that works within SLA defined maintenance windows
• Licensing -- minimize license costs (server consolidation, right-sizing of physical solution)
• Cost -- Overall costs must be forecasted at design stage and design must be built to within assigned budget ranges ... the system designer needs to communicate with management and 'users' and properly (re)set expectations of both parties.

System Design is a multi-discipline action, the designer must be aware of the overall end goal and all of the related pieces ... a system design must be tuned to a particular application and knowledge of that application must be within the designer's grasp or there will be a mismatch that might mean wasted or insufficient resources.