Partitioning and Redundancy?
System is Partitionable
- To isolate faults
- To enable online repair/recovery
- To enable online HW growth/SW upgrade
- To enable operator training/expand experience on portions of real system without fear of system failure
- Techniques: Geographically replicated sites, Virtual Machine Monitors
System is Redundant
- Sufficient HW redundancy/Data replication => part of system down but satisfactory service still available
- Enough to survive 2nd (nth?) failure during recovery
- Techniques: RAID-6, N-copies of data