{"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":"Strong 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2020, S3 was eventually consistent for overwrites:\nPUT key=X, val=A → GET key=X → might return old value or 404","originalText":"Before 2020, S3 was eventually consistent for overwrites:\nPUT key=X, val=A → GET key=X → might return old value or 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design (and S3 since Dec 2020): STRONG consistency","originalText":"Modern design (and S3 since Dec 2020): STRONG 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PUT arrives at API gateway\n2. Write data to storage nodes (at least 2 of 3 AZs)\n3. Update metadata (strongly consistent — quorum write)\n4. Return 200 to client only after BOTH data + metadata commit","originalText":"1. PUT arrives at API gateway\n2. Write data to storage nodes (at least 2 of 3 AZs)\n3. Update metadata (strongly consistent — quorum write)\n4. Return 200 to client only after BOTH data + metadata commit","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":571.4000000000001,"width":563.8413999999999,"height":129.60000000000002,"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":589.4000000000001,"width":523.8413999999999,"height":93.60000000000001,"fontSize":18,"fontFamily":1,"text":"5. Subsequent GET:\n→ Read metadata (quorum read — sees latest version)\n→ Fetch data from locations in metadata\n→ Always returns the latest PUT","originalText":"5. Subsequent GET:\n→ Read metadata (quorum read — sees latest version)\n→ Fetch data from locations in metadata\n→ Always returns the latest PUT","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":726.0000000000001,"width":639.51268,"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":744.0000000000001,"width":599.51268,"height":93.60000000000001,"fontSize":18,"fontFamily":1,"text":"Implementation:\n• Metadata store uses Raft/Paxos → linearizable reads/writes\n• \"Witnesses\" at each layer ensure read sees latest write\n• Clock sync (TrueTime / HLC) for ordering concurrent writes","originalText":"Implementation:\n• Metadata store uses Raft/Paxos → linearizable reads/writes\n• \"Witnesses\" at each layer ensure read sees latest write\n• Clock sync (TrueTime / HLC) for ordering concurrent writes","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":880.6000000000001,"width":576.4342,"height":106.2,"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":898.6000000000001,"width":536.4342,"height":70.2,"fontSize":18,"fontFamily":1,"text":"Cost of strong consistency:\n• ~1-2 ms added latency (quorum overhead)\n• Worth it: eliminates entire class of bugs for customers","originalText":"Cost of strong consistency:\n• ~1-2 ms added latency (quorum overhead)\n• Worth it: eliminates entire class of bugs for customers","textAlign":"left","verticalAlign":"middle","containerId":"shape-14","lineHeight":1.3,"autoResize":false,"customData":{"revealStep":8}}],"appState":{"viewBackgroundColor":"#fbfbf8","gridSize":null},"files":{}}