1.5. Reflection Checkpoint
Key Takeaways
Before proceeding, ensure you can:
- Explain why servers use ECC RAM, redundant PSUs, and hot-swap drives—not as features, but as consequences of the shared-service reliability requirement
- Calculate availability from MTBF and MTTR, and explain how both reliability and serviceability improvements increase availability
- Describe all four server lifecycle phases and identify the key risk at each phase
- Distinguish hardware failure patterns (consistent, physical indicators) from software failure patterns (intermittent, behavioral)
- Apply the dependency stack to determine where to start troubleshooting a multi-layer problem
Connecting Forward
In Phase 2, you'll apply these mental models to concrete hardware: how to physically install and configure the servers and storage that implement these principles. When you read about RAID levels, think about reliability. When you read about out-of-band management, think about serviceability. When you read about the HCL, think about the deployment phase of the lifecycle.
Self-Check Questions
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A server has been running for 3 years and begins crashing randomly. You check hardware diagnostics and everything tests clean. According to the failure mode patterns from this phase, what category of failure should you investigate next, and why?
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Your organization has an RTO of 4 hours and an RPO of 1 hour. What does each of these require of your disaster recovery design, and which is harder to achieve?
