{"abstract":"Stripes with silent corruption are returned as valid data.","category":"Error-correcting codes","checks":8,"contract":"RAID-5 left-symmetric layout on n >= 3 disks: in stripe s the parity lives on disk n-1-(s mod n) and data chunk j lives on disk (parity + 1 + j) mod n. blocks lists the stripe per disk (ints; at most one None for a failed disk). A missing block is rebuilt by XOR; with no missing block the XOR of all blocks must be 0 or the result is \"parity-mismatch\". Return [data chunks in logical order, parity block].","contract_signature":"blocks, stripe, n","evaluation_group":"w2-error_correcting_codes-raid5-left-symmetric","failed_approach":"Checking only the data blocks for XOR zero rejects most healthy stripes.","family":"w2-error_correcting_codes-raid5-left-symmetric-scrub-check","id":"FA-72041","implementations":{"attempt":{"sha256":"bbc720ea54713eb8fd9b3b3b4a5c80d9c17e34db1f8e6ebd75a0327e323edaaa","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(blocks, stripe, n):\n    if n < 3 or len(blocks) != n or blocks.count(None) > 1:\n        return None\n    pd = n - 1 - stripe % n\n    if None in blocks:\n        m = blocks.index(None)\n        x = 0\n        for k, v in enumerate(blocks):\n            if k != m:\n                x ^= v\n        blocks = blocks[:m] + [x] + blocks[m + 1:]\n    else:\n        x = 0\n        for k, v in enumerate(blocks):\n            if k != pd:\n                x ^= v\n        if x != 0:\n            return 'parity-mismatch'\n    order = [(pd + 1 + j) % n for j in range(n - 1)]\n    return [[blocks[d] for d in order], blocks[pd]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['regression [[133, 23, 147], 0, 3]', [[133, 23, 147], 0, 3], 'parity-mismatch'], ['regression [[81, 29, 77], 1, 3]', [[81, 29, 77], 1, 3], 'parity-mismatch'], ['partial-repair [[132, 23, 147], 0, 3]', [[132, 23, 147], 0, 3], [[132, 23], 147]], ['partial-repair [[80, 29, 77], 1, 3]', [[80, 29, 77], 1, 3], [[77, 80], 29]], ['control [[132, null, 147], 0, 3]', [[132, None, 147], 0, 3], [[132, 23], 147]], ['control [[80, null, 77], 1, 3]', [[80, None, 77], 1, 3], [[77, 80], 29]], ['control [[166, null, 235, 175], 0, 4]', [[166, None, 235, 175], 0, 4], [[166, 226, 235], 175]], ['control [[197, null, 1, 70], 1, 4]', [[197, None, 1, 70], 1, 4], [[70, 197, 130], 1]]], [['regression [[196, 130, 1, 70], 1, 4]', [[196, 130, 1, 70], 1, 4], 'parity-mismatch'], ['regression [[203, 146, 183, 239], 2, 4]', [[203, 146, 183, 239], 2, 4], 'parity-mismatch'], ['partial-repair [[197, 130, 1, 70], 1, 4]', [[197, 130, 1, 70], 1, 4], [[70, 197, 130], 1]], ['control [[96, 103, null, 49], 3, 4]', [[96, 103, None, 49], 3, 4], [[103, 54, 49], 96]], ['control [[45, 55, null, 192, 118], 2, 5]', [[45, 55, None, 192, 118], 2, 5], [[192, 118, 45, 55], 172]], ['control [[95, 206, 36, null, 230], 6, 5]', [[95, 206, 36, None, 230], 6, 5], [[230, 95, 206, 36], 83]], ['control [[null, 163, 83, 128, 142, 206], 4, 6]', [[None, 163, 83, 128, 142, 206], 4, 6], [[83, 128, 142, 206, 48], 163]], ['control [[null, 132, 216, 194], 5, 4]', [[None, 132, 216, 194], 5, 4], [[194, 158, 132], 216]]], [['regression [[44, 55, 172, 192, 118], 2, 5]', [[44, 55, 172, 192, 118], 2, 5], 'parity-mismatch'], ['regression [[94, 206, 36, 83, 230], 6, 5]', [[94, 206, 36, 83, 230], 6, 5], 'parity-mismatch'], ['partial-repair [[96, 103, 54, 49], 3, 4]', [[96, 103, 54, 49], 3, 4], [[103, 54, 49], 96]], ['partial-repair [[45, 55, 172, 192, 118], 2, 5]', [[45, 55, 172, 192, 118], 2, 5], [[192, 118, 45, 55], 172]], ['control [[null, 127, 108], 2, 3]', [[None, 127, 108], 2, 3], [[127, 108], 19]], ['control [[135, null, 201, 163, 114], 0, 5]', [[135, None, 201, 163, 114], 0, 5], [[135, 159, 201, 163], 114]], ['control [[1, null, null], 0, 3]', [[1, None, None], 0, 3], None], ['control [[1, 2], 0, 2]', [[1, 2], 0, 2], None]], [['regression [[159, 132, 216, 194], 5, 4]', [[159, 132, 216, 194], 5, 4], 'parity-mismatch'], ['regression [[18, 127, 108], 2, 3]', [[18, 127, 108], 2, 3], 'parity-mismatch'], ['partial-repair [[48, 163, 83, 128, 142, 206], 4, 6]', [[48, 163, 83, 128, 142, 206], 4, 6], [[83, 128, 142, 206, 48], 163]], ['partial-repair [[158, 132, 216, 194], 5, 4]', [[158, 132, 216, 194], 5, 4], [[194, 158, 132], 216]], ['control [[132, null, 147], 0, 3]', [[132, None, 147], 0, 3], [[132, 23], 147]], ['control [[80, null, 77], 1, 3]', [[80, None, 77], 1, 3], [[77, 80], 29]], ['control [[166, null, 235, 175], 0, 4]', [[166, None, 235, 175], 0, 4], [[166, 226, 235], 175]], ['control [[197, null, 1, 70], 1, 4]', [[197, None, 1, 70], 1, 4], [[70, 197, 130], 1]]], [['regression [[133, 23, 147], 0, 3]', [[133, 23, 147], 0, 3], 'parity-mismatch'], ['regression [[81, 29, 77], 1, 3]', [[81, 29, 77], 1, 3], 'parity-mismatch'], ['partial-repair [[135, 159, 201, 163, 114], 0, 5]', [[135, 159, 201, 163, 114], 0, 5], [[135, 159, 201, 163], 114]], ['partial-repair [[132, 23, 147], 0, 3]', [[132, 23, 147], 0, 3], [[132, 23], 147]], ['control [[96, 103, null, 49], 3, 4]', [[96, 103, None, 49], 3, 4], [[103, 54, 49], 96]], ['control [[45, 55, null, 192, 118], 2, 5]', [[45, 55, None, 192, 118], 2, 5], [[192, 118, 45, 55], 172]], ['control [[95, 206, 36, null, 230], 6, 5]', [[95, 206, 36, None, 230], 6, 5], [[230, 95, 206, 36], 83]], ['control [[null, 163, 83, 128, 142, 206], 4, 6]', [[None, 163, 83, 128, 142, 206], 4, 6], [[83, 128, 142, 206, 48], 163]]]]\nfor label, args, expected in fixtures[N - 1]:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"be03e5282c3aebf36b293203277ce68e78a2ab65dd9dbe5c9205995bc2993b22","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(blocks, stripe, n):\n    if n < 3 or len(blocks) != n or blocks.count(None) > 1:\n        return None\n    pd = n - 1 - stripe % n\n    if None in blocks:\n        m = blocks.index(None)\n        x = 0\n        for k, v in enumerate(blocks):\n            if k != m:\n                x ^= v\n        blocks = blocks[:m] + [x] + blocks[m + 1:]\n    else:\n        x = 0\n        for v in blocks:\n            x ^= v\n    order = [(pd + 1 + j) % n for j in range(n - 1)]\n    return [[blocks[d] for d in order], blocks[pd]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['regression [[133, 23, 147], 0, 3]', [[133, 23, 147], 0, 3], 'parity-mismatch'], ['regression [[81, 29, 77], 1, 3]', [[81, 29, 77], 1, 3], 'parity-mismatch'], ['partial-repair [[132, 23, 147], 0, 3]', [[132, 23, 147], 0, 3], [[132, 23], 147]], ['partial-repair [[80, 29, 77], 1, 3]', [[80, 29, 77], 1, 3], [[77, 80], 29]], ['control [[132, null, 147], 0, 3]', [[132, None, 147], 0, 3], [[132, 23], 147]], ['control [[80, null, 77], 1, 3]', [[80, None, 77], 1, 3], [[77, 80], 29]], ['control [[166, null, 235, 175], 0, 4]', [[166, None, 235, 175], 0, 4], [[166, 226, 235], 175]], ['control [[197, null, 1, 70], 1, 4]', [[197, None, 1, 70], 1, 4], [[70, 197, 130], 1]]], [['regression [[196, 130, 1, 70], 1, 4]', [[196, 130, 1, 70], 1, 4], 'parity-mismatch'], ['regression [[203, 146, 183, 239], 2, 4]', [[203, 146, 183, 239], 2, 4], 'parity-mismatch'], ['partial-repair [[197, 130, 1, 70], 1, 4]', [[197, 130, 1, 70], 1, 4], [[70, 197, 130], 1]], ['control [[96, 103, null, 49], 3, 4]', [[96, 103, None, 49], 3, 4], [[103, 54, 49], 96]], ['control [[45, 55, null, 192, 118], 2, 5]', [[45, 55, None, 192, 118], 2, 5], [[192, 118, 45, 55], 172]], ['control [[95, 206, 36, null, 230], 6, 5]', [[95, 206, 36, None, 230], 6, 5], [[230, 95, 206, 36], 83]], ['control [[null, 163, 83, 128, 142, 206], 4, 6]', [[None, 163, 83, 128, 142, 206], 4, 6], [[83, 128, 142, 206, 48], 163]], ['control [[null, 132, 216, 194], 5, 4]', [[None, 132, 216, 194], 5, 4], [[194, 158, 132], 216]]], [['regression [[44, 55, 172, 192, 118], 2, 5]', [[44, 55, 172, 192, 118], 2, 5], 'parity-mismatch'], ['regression [[94, 206, 36, 83, 230], 6, 5]', [[94, 206, 36, 83, 230], 6, 5], 'parity-mismatch'], ['partial-repair [[96, 103, 54, 49], 3, 4]', [[96, 103, 54, 49], 3, 4], [[103, 54, 49], 96]], ['partial-repair [[45, 55, 172, 192, 118], 2, 5]', [[45, 55, 172, 192, 118], 2, 5], [[192, 118, 45, 55], 172]], ['control [[null, 127, 108], 2, 3]', [[None, 127, 108], 2, 3], [[127, 108], 19]], ['control [[135, null, 201, 163, 114], 0, 5]', [[135, None, 201, 163, 114], 0, 5], [[135, 159, 201, 163], 114]], ['control [[1, null, null], 0, 3]', [[1, None, None], 0, 3], None], ['control [[1, 2], 0, 2]', [[1, 2], 0, 2], None]], [['regression [[159, 132, 216, 194], 5, 4]', [[159, 132, 216, 194], 5, 4], 'parity-mismatch'], ['regression [[18, 127, 108], 2, 3]', [[18, 127, 108], 2, 3], 'parity-mismatch'], ['partial-repair [[48, 163, 83, 128, 142, 206], 4, 6]', [[48, 163, 83, 128, 142, 206], 4, 6], [[83, 128, 142, 206, 48], 163]], ['partial-repair [[158, 132, 216, 194], 5, 4]', [[158, 132, 216, 194], 5, 4], [[194, 158, 132], 216]], ['control [[132, null, 147], 0, 3]', [[132, None, 147], 0, 3], [[132, 23], 147]], ['control [[80, null, 77], 1, 3]', [[80, None, 77], 1, 3], [[77, 80], 29]], ['control [[166, null, 235, 175], 0, 4]', [[166, None, 235, 175], 0, 4], [[166, 226, 235], 175]], ['control [[197, null, 1, 70], 1, 4]', [[197, None, 1, 70], 1, 4], [[70, 197, 130], 1]]], [['regression [[133, 23, 147], 0, 3]', [[133, 23, 147], 0, 3], 'parity-mismatch'], ['regression [[81, 29, 77], 1, 3]', [[81, 29, 77], 1, 3], 'parity-mismatch'], ['partial-repair [[135, 159, 201, 163, 114], 0, 5]', [[135, 159, 201, 163, 114], 0, 5], [[135, 159, 201, 163], 114]], ['partial-repair [[132, 23, 147], 0, 3]', [[132, 23, 147], 0, 3], [[132, 23], 147]], ['control [[96, 103, null, 49], 3, 4]', [[96, 103, None, 49], 3, 4], [[103, 54, 49], 96]], ['control [[45, 55, null, 192, 118], 2, 5]', [[45, 55, None, 192, 118], 2, 5], [[192, 118, 45, 55], 172]], ['control [[95, 206, 36, null, 230], 6, 5]', [[95, 206, 36, None, 230], 6, 5], [[230, 95, 206, 36], 83]], ['control [[null, 163, 83, 128, 142, 206], 4, 6]', [[None, 163, 83, 128, 142, 206], 4, 6], [[83, 128, 142, 206, 48], 163]]]]\nfor label, args, expected in fixtures[N - 1]:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":"A deterministic, bounded teaching model of the named code under the stated contract; not a production codec. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"w2-error_correcting_codes-raid5-left-symmetric-scrub-check","generated_at":"2026-09-29T14:48:34.973306+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Array controllers rebuild degraded stripes and must map disks to logical chunks correctly.","root_cause":"The XOR-to-zero check of a complete stripe is missing.","sha256":"32b89e773f664b64a817a84e65636375f0906ae2283b7887c97410d64023db77","title":"RAID-5 skips the parity consistency check · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":40.344,"exit_code":1,"observations":[{"actual":"parity-mismatch","check":"regression [[133, 23, 147], 0, 3]","expected":"parity-mismatch","passed":true},{"actual":"parity-mismatch","check":"regression [[81, 29, 77], 1, 3]","expected":"parity-mismatch","passed":true},{"actual":"parity-mismatch","check":"partial-repair [[132, 23, 147], 0, 3]","expected":[[132,23],147],"passed":false},{"actual":"parity-mismatch","check":"partial-repair [[80, 29, 77], 1, 3]","expected":[[77,80],29],"passed":false},{"actual":[[132,23],147],"check":"control [[132, null, 147], 0, 3]","expected":[[132,23],147],"passed":true},{"actual":[[77,80],29],"check":"control [[80, null, 77], 1, 3]","expected":[[77,80],29],"passed":true},{"actual":[[166,226,235],175],"check":"control [[166, null, 235, 175], 0, 4]","expected":[[166,226,235],175],"passed":true},{"actual":[[70,197,130],1],"check":"control [[197, null, 1, 70], 1, 4]","expected":[[70,197,130],1],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression [[133, 23, 147], 0, 3]\", \"actual\": \"parity-mismatch\", \"expected\": \"parity-mismatch\", \"passed\": true}, {\"check\": \"regression [[81, 29, 77], 1, 3]\", \"actual\": \"parity-mismatch\", \"expected\": \"parity-mismatch\", \"passed\": true}, {\"check\": \"partial-repair [[132, 23, 147], 0, 3]\", \"actual\": \"parity-mismatch\", \"expected\": [[132, 23], 147], \"passed\": false}, {\"check\": \"partial-repair [[80, 29, 77], 1, 3]\", \"actual\": \"parity-mismatch\", \"expected\": [[77, 80], 29], \"passed\": false}, {\"check\": \"control [[132, null, 147], 0, 3]\", \"actual\": [[132, 23], 147], \"expected\": [[132, 23], 147], \"passed\": true}, {\"check\": \"control [[80, null, 77], 1, 3]\", \"actual\": [[77, 80], 29], \"expected\": [[77, 80], 29], \"passed\": true}, {\"check\": \"control [[166, null, 235, 175], 0, 4]\", \"actual\": [[166, 226, 235], 175], \"expected\": [[166, 226, 235], 175], \"passed\": true}, {\"check\": \"control [[197, null, 1, 70], 1, 4]\", \"actual\": [[70, 197, 130], 1], \"expected\": [[70, 197, 130], 1], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":40.585,"exit_code":1,"observations":[{"actual":[[133,23],147],"check":"regression [[133, 23, 147], 0, 3]","expected":"parity-mismatch","passed":false},{"actual":[[77,81],29],"check":"regression [[81, 29, 77], 1, 3]","expected":"parity-mismatch","passed":false},{"actual":[[132,23],147],"check":"partial-repair [[132, 23, 147], 0, 3]","expected":[[132,23],147],"passed":true},{"actual":[[77,80],29],"check":"partial-repair [[80, 29, 77], 1, 3]","expected":[[77,80],29],"passed":true},{"actual":[[132,23],147],"check":"control [[132, null, 147], 0, 3]","expected":[[132,23],147],"passed":true},{"actual":[[77,80],29],"check":"control [[80, null, 77], 1, 3]","expected":[[77,80],29],"passed":true},{"actual":[[166,226,235],175],"check":"control [[166, null, 235, 175], 0, 4]","expected":[[166,226,235],175],"passed":true},{"actual":[[70,197,130],1],"check":"control [[197, null, 1, 70], 1, 4]","expected":[[70,197,130],1],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression [[133, 23, 147], 0, 3]\", \"actual\": [[133, 23], 147], \"expected\": \"parity-mismatch\", \"passed\": false}, {\"check\": \"regression [[81, 29, 77], 1, 3]\", \"actual\": [[77, 81], 29], \"expected\": \"parity-mismatch\", \"passed\": false}, {\"check\": \"partial-repair [[132, 23, 147], 0, 3]\", \"actual\": [[132, 23], 147], \"expected\": [[132, 23], 147], \"passed\": true}, {\"check\": \"partial-repair [[80, 29, 77], 1, 3]\", \"actual\": [[77, 80], 29], \"expected\": [[77, 80], 29], \"passed\": true}, {\"check\": \"control [[132, null, 147], 0, 3]\", \"actual\": [[132, 23], 147], \"expected\": [[132, 23], 147], \"passed\": true}, {\"check\": \"control [[80, null, 77], 1, 3]\", \"actual\": [[77, 80], 29], \"expected\": [[77, 80], 29], \"passed\": true}, {\"check\": \"control [[166, null, 235, 175], 0, 4]\", \"actual\": [[166, 226, 235], 175], \"expected\": [[166, 226, 235], 175], \"passed\": true}, {\"check\": \"control [[197, null, 1, 70], 1, 4]\", \"actual\": [[70, 197, 130], 1], \"expected\": [[70, 197, 130], 1], \"passed\": true}], \"passed\": false}\n"}},"member_only":{"stages":["fixed"],"fields":["implementations.fixed","verification.fixed","harness","repair"],"note":"The verified repair, its recorded checks, the repair description, and the scoring harness are available to members."}}