System Fundamentals: Deploying, Changing and Protecting Systems
Topic 1 examines how computer systems are deployed inside organizations - what a system is made of, how a new system is installed and changed, and how it is backed up and supported. Exam questions are almost always scenario-based: you are given a school, hospital or business and must justify a choice rather than name a term.
Components and architectures
- A system is hardware, software, data, people and procedures - not just machines.
- Client–server: a central server provides services; easier to manage and secure, but a single point of failure. Peer-to-peer: each node shares directly; cheap for small networks, weak central control.
- Thin client (little local processing, relies on the server) versus thick client (local processing and storage). Thin clients suit situations where cost, central management and data security dominate.
- Legacy systems persist because replacement cost or risk is high; they create interoperability problems, so data migration and testing must be planned.
Installing and changing systems
Four conversion methods: direct changeover (fast, cheap, high risk), parallel running (safe, duplicated work), phased conversion (part by part), pilot (one site first). Supporting activities include data migration, testing, staff training, user documentation and a rollback plan. Backups: full; incremental (only data changed since the last backup of any type); differential (everything changed since the last full backup). Keep copies off-site - RAID improves availability but is not a backup.
Worked example
A hospital replaces its patient-records system. Recommended: parallel running for one full term. Reasoning: records are life-critical, so a failed cutover is unacceptable; running old and new systems together lets staff compare output and fall back with no data loss. The cost - duplicate data entry and two licences - is accepted because the risk of direct changeover outweighs it. The marks come from the sentences linking method to risk, not from naming the method.
Traps that cost marks
- Naming a conversion method without justification earns at most the first mark.
- Confusing incremental with differential backups.
- Claiming RAID or cloud storage is itself a backup strategy.
- Describing direct changeover as cheaper without acknowledging the risk.