{"type":"excalidraw","version":2,"source":"https://AwesomeSystemDesign.dev","elements":[{"angle":0,"strokeColor":"#628572","backgroundColor":"#edf5ee","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-1"],"frameId":null,"roundness":null,"boundElements":[{"type":"text","id":"shape-1"}],"updated":0,"link":null,"locked":false,"id":"shape-0","type":"rectangle","seed":41,"x":30,"y":30,"width":420,"height":68,"customData":{"revealStep":1}},{"angle":0,"strokeColor":"#394557","backgroundColor":"transparent","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-1"],"frameId":null,"roundness":null,"boundElements":null,"updated":0,"link":null,"locked":false,"id":"shape-1","type":"text","seed":114,"x":50,"y":52.3,"width":380,"height":23.400000000000002,"fontSize":18,"fontFamily":1,"text":"Annual Durability Calculation","originalText":"Annual Durability Calculation","textAlign":"left","verticalAlign":"middle","containerId":"shape-0","lineHeight":1.3,"autoResize":false,"customData":{"revealStep":1}},{"angle":0,"strokeColor":"#a68a53","backgroundColor":"#fff7e6","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-2"],"frameId":null,"roundness":null,"boundElements":[{"type":"text","id":"shape-3"}],"updated":0,"link":null,"locked":false,"id":"shape-2","type":"rectangle","seed":187,"x":30,"y":123,"width":602.42116,"height":153,"customData":{"revealStep":2}},{"angle":0,"strokeColor":"#394557","backgroundColor":"transparent","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-2"],"frameId":null,"roundness":null,"boundElements":null,"updated":0,"link":null,"locked":false,"id":"shape-3","type":"text","seed":260,"x":50,"y":141,"width":562.42116,"height":117,"fontSize":18,"fontFamily":1,"text":"Assumptions:\n• Disk Annual Failure Rate (AFR) = 2%\n• Replication factor = 3 (across 3 AZs)\n• Mean Time To Repair (MTTR) = 4 hours\n• Chunks per disk = 3,000 (64 MB chunks on 200 TB disk)","originalText":"Assumptions:\n• Disk Annual Failure Rate (AFR) = 2%\n• Replication factor = 3 (across 3 AZs)\n• Mean Time To Repair (MTTR) = 4 hours\n• Chunks per disk = 3,000 (64 MB chunks on 200 TB disk)","textAlign":"left","verticalAlign":"middle","containerId":"shape-2","lineHeight":1.3,"autoResize":false,"customData":{"revealStep":2}},{"angle":0,"strokeColor":"#9180ac","backgroundColor":"#f4effb","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-3"],"frameId":null,"roundness":null,"boundElements":[{"type":"text","id":"shape-5"}],"updated":0,"link":null,"locked":false,"id":"shape-4","type":"rectangle","seed":333,"x":30,"y":301,"width":420,"height":68,"customData":{"revealStep":3}},{"angle":0,"strokeColor":"#394557","backgroundColor":"transparent","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-3"],"frameId":null,"roundness":null,"boundElements":null,"updated":0,"link":null,"locked":false,"id":"shape-5","type":"text","seed":406,"x":50,"y":323.3,"width":380,"height":23.400000000000002,"fontSize":18,"fontFamily":1,"text":"P(single disk fails in a year) = 0.02","originalText":"P(single disk fails in a year) = 0.02","textAlign":"left","verticalAlign":"middle","containerId":"shape-4","lineHeight":1.3,"autoResize":false,"customData":{"revealStep":3}},{"angle":0,"strokeColor":"#6577aa","backgroundColor":"#eef1fc","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-4"],"frameId":null,"roundness":null,"boundElements":[{"type":"text","id":"shape-7"}],"updated":0,"link":null,"locked":false,"id":"shape-6","type":"rectangle","seed":479,"x":30,"y":394,"width":530.0698,"height":82.80000000000001,"customData":{"revealStep":4}},{"angle":0,"strokeColor":"#394557","backgroundColor":"transparent","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-4"],"frameId":null,"roundness":null,"boundElements":null,"updated":0,"link":null,"locked":false,"id":"shape-7","type":"text","seed":552,"x":50,"y":412,"width":490.0698,"height":46.800000000000004,"fontSize":18,"fontFamily":1,"text":"P(2nd replica disk fails during 4-hour repair window):\n= 0.02 × (4 / 8760) = 9.13 × 10⁻⁶","originalText":"P(2nd replica disk fails during 4-hour repair window):\n= 0.02 × (4 / 8760) = 9.13 × 10⁻⁶","textAlign":"left","verticalAlign":"middle","containerId":"shape-6","lineHeight":1.3,"autoResize":false,"customData":{"revealStep":4}},{"angle":0,"strokeColor":"#628572","backgroundColor":"#edf5ee","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-5"],"frameId":null,"roundness":null,"boundElements":[{"type":"text","id":"shape-9"}],"updated":0,"link":null,"locked":false,"id":"shape-8","type":"rectangle","seed":625,"x":30,"y":501.8,"width":474.7378,"height":82.80000000000001,"customData":{"revealStep":5}},{"angle":0,"strokeColor":"#394557","backgroundColor":"transparent","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-5"],"frameId":null,"roundness":null,"boundElements":null,"updated":0,"link":null,"locked":false,"id":"shape-9","type":"text","seed":698,"x":50,"y":519.8000000000001,"width":434.7378,"height":46.800000000000004,"fontSize":18,"fontFamily":1,"text":"P(3rd replica disk also fails in same 4 hours):\n= 9.13 × 10⁻⁶ × (4 / 8760) = 4.17 × 10⁻⁹","originalText":"P(3rd replica disk also fails in same 4 hours):\n= 9.13 × 10⁻⁶ × (4 / 8760) = 4.17 × 10⁻⁹","textAlign":"left","verticalAlign":"middle","containerId":"shape-8","lineHeight":1.3,"autoResize":false,"customData":{"revealStep":5}},{"angle":0,"strokeColor":"#a68a53","backgroundColor":"#fff7e6","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-6"],"frameId":null,"roundness":null,"boundElements":[{"type":"text","id":"shape-11"}],"updated":0,"link":null,"locked":false,"id":"shape-10","type":"rectangle","seed":771,"x":30,"y":609.6,"width":420,"height":82.80000000000001,"customData":{"revealStep":6}},{"angle":0,"strokeColor":"#394557","backgroundColor":"transparent","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-6"],"frameId":null,"roundness":null,"boundElements":null,"updated":0,"link":null,"locked":false,"id":"shape-11","type":"text","seed":844,"x":50,"y":627.6,"width":380,"height":46.800000000000004,"fontSize":18,"fontFamily":1,"text":"P(losing one specific chunk in a year):\n≈ 4.17 × 10⁻⁹ per chunk","originalText":"P(losing one specific chunk in a year):\n≈ 4.17 × 10⁻⁹ per chunk","textAlign":"left","verticalAlign":"middle","containerId":"shape-10","lineHeight":1.3,"autoResize":false,"customData":{"revealStep":6}},{"angle":0,"strokeColor":"#9180ac","backgroundColor":"#f4effb","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-7"],"frameId":null,"roundness":null,"boundElements":[{"type":"text","id":"shape-13"}],"updated":0,"link":null,"locked":false,"id":"shape-12","type":"rectangle","seed":917,"x":30,"y":717.4000000000001,"width":532.87456,"height":129.60000000000002,"customData":{"revealStep":7}},{"angle":0,"strokeColor":"#394557","backgroundColor":"transparent","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-7"],"frameId":null,"roundness":null,"boundElements":null,"updated":0,"link":null,"locked":false,"id":"shape-13","type":"text","seed":990,"x":50,"y":735.4000000000001,"width":492.87456,"height":93.60000000000001,"fontSize":18,"fontFamily":1,"text":"For 100 trillion chunks:\nExpected chunks lost = 100T × 4.17 × 10⁻⁹ ≈\n417,000\n... that's too many!","originalText":"For 100 trillion chunks:\nExpected chunks lost = 100T × 4.17 × 10⁻⁹ ≈\n417,000\n... that's too many!","textAlign":"left","verticalAlign":"middle","containerId":"shape-12","lineHeight":1.3,"autoResize":false,"customData":{"revealStep":7}},{"angle":0,"strokeColor":"#6577aa","backgroundColor":"#eef1fc","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-8"],"frameId":null,"roundness":null,"boundElements":[{"type":"text","id":"shape-15"}],"updated":0,"link":null,"locked":false,"id":"shape-14","type":"rectangle","seed":1063,"x":30,"y":872.0000000000001,"width":572.5228000000001,"height":129.60000000000002,"customData":{"revealStep":8}},{"angle":0,"strokeColor":"#394557","backgroundColor":"transparent","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-8"],"frameId":null,"roundness":null,"boundElements":null,"updated":0,"link":null,"locked":false,"id":"shape-15","type":"text","seed":1136,"x":50,"y":890.0000000000001,"width":532.5228000000001,"height":93.60000000000001,"fontSize":18,"fontFamily":1,"text":"Solution: Faster repair + more replicas for critical data\nWith MTTR = 1 hour and awareness-based placement:\nP(data loss per chunk) ≈ 10⁻¹²\nExpected losses at 100T chunks = 0.1 per year ✅","originalText":"Solution: Faster repair + more replicas for critical data\nWith MTTR = 1 hour and awareness-based placement:\nP(data loss per chunk) ≈ 10⁻¹²\nExpected losses at 100T chunks = 0.1 per year ✅","textAlign":"left","verticalAlign":"middle","containerId":"shape-14","lineHeight":1.3,"autoResize":false,"customData":{"revealStep":8}},{"angle":0,"strokeColor":"#628572","backgroundColor":"#edf5ee","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-9"],"frameId":null,"roundness":null,"boundElements":[{"type":"text","id":"shape-17"}],"updated":0,"link":null,"locked":false,"id":"shape-16","type":"rectangle","seed":1209,"x":30,"y":1026.6000000000001,"width":626.63368,"height":153,"customData":{"revealStep":9}},{"angle":0,"strokeColor":"#394557","backgroundColor":"transparent","fillStyle":"solid","strokeWidth":1.5,"strokeStyle":"solid","roughness":0.7,"opacity":100,"version":1,"versionNonce":1,"isDeleted":false,"groupIds":["step-9"],"frameId":null,"roundness":null,"boundElements":null,"updated":0,"link":null,"locked":false,"id":"shape-17","type":"text","seed":1282,"x":50,"y":1044.6000000000001,"width":586.63368,"height":117,"fontSize":18,"fontFamily":1,"text":"Additional measures:\n• Rack-aware placement (replicas on different racks)\n• Correlated failure detection (if disk A fails, proactively\nadd extra replicas for chunks that share a node with disk A)\n• Scrubbing detects bit rot before it's needed for repair","originalText":"Additional measures:\n• Rack-aware placement (replicas on different racks)\n• Correlated failure detection (if disk A fails, proactively\nadd extra replicas for chunks that share a node with disk A)\n• Scrubbing detects bit rot before it's needed for repair","textAlign":"left","verticalAlign":"middle","containerId":"shape-16","lineHeight":1.3,"autoResize":false,"customData":{"revealStep":9}}],"appState":{"viewBackgroundColor":"#fbfbf8","gridSize":null},"files":{}}