RAID Capacity & Fault-Tolerance Calculator implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t4-040

Effect

Computation or source lookup only

Input and validation requirements

The zero-drive input causes a negative usable-capacity result and an undefined redundancy-overhead division by zero, so the instrument must reject it. The unit ambiguity can also produce materially different byte capacities unless TB versus TiB is made explicit.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "raid_level": "RAID0",
    "number_of_drives": 4,
    "drive_capacity": 2,
    "capacity_unit": "decimal TB"
  },
  "expected_outputs": {
    "usable_capacity": 8,
    "capacity_unit": "TB",
    "redundancy_overhead_percent": 0,
    "tolerated_simultaneous_failures": 0,
    "rebuild_risk_note": "No redundancy; any single drive failure loses the array. Vendor- and workload-specific rebuild/URE analysis is not performed."
  },
  "working": "Raw capacity = N×S = 4×2 = 8 TB. Usable capacity = 4×2 = 8 TB. Redundancy overhead = (8−8)/8×100 = 0/8×100 = 0%. RAID0 tolerated failures = 0."
}

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche4/tranche4-results.json