2.2. Storage Deployment and Management
💡 First Principle: Storage is where servers keep everything that matters. Every storage decision involves a trade-off among three competing factors: performance, capacity, and redundancy. You cannot fully optimize all three simultaneously—understanding these trade-offs is what drives correct storage design choices.
Consider: RAID 0 maximizes performance and capacity but offers zero redundancy. RAID 1 maximizes redundancy but halves usable capacity and adds write overhead. RAID 5 balances all three but is vulnerable during rebuild. The exam asks you to choose the right RAID for a given scenario—which means you need to understand these trade-offs, not just memorize RAID level definitions.
⚠️ Common Misconception: RAID 5 can safely survive any single drive failure. It can survive the failure—but the rebuild process exposes a critical window of vulnerability. If a second drive fails during rebuild (which can take 12–48 hours on modern large drives), all data is lost. RAID 6 adds a second parity drive specifically to protect against this "double failure" scenario.
