{
  "slug": "backblaze-q4-2025-old-age-by-model",
  "title": "Which models make up the 6+ year AFR buckets, Backblaze Q4 2025",
  "kind": "dataset",
  "summary": "Splits the older power-on age buckets (6 to under 7, 7 to under 8, 8 or more years) of Backblaze's Q4 2025 fleet (October 1 to December 31, 2025) by drive model, from the raw daily Drive Stats files. Sample: hard drives of 3 TB or more with a power-on-hours value; 1,424,836, 226,691 and 1,383,760 drive days in the three buckets, with 101, 44 and 70 failures. In the 7 to under 8 year bucket (7.08% AFR), two models hold 27 plus 13 of the 44 failures: HGST HUH728080ALE600 and Toshiba MG07ACA14TA. Association only, one fleet and one quarter.",
  "license": "Derivative table computed from the Backblaze Drive Stats daily files for Q4 2025. Cite Backblaze if you use it. You are solely responsible for how you use it. Backblaze's dataset page allows sale of derivative works and forbids selling the Drive Stats data itself. This CSV is a 36-row aggregate, not the daily SMART archive, and that archive is not for sale.",
  "licenseUrl": "https://www.backblaze.com/cloud-storage/resources/hard-drive-test-data",
  "sourceUrl": "https://www.backblaze.com/cloud-storage/resources/hard-drive-test-data",
  "accessed": "2026-10-10",
  "rowCount": 36,
  "columns": [
    {
      "name": "age_years",
      "type": "string",
      "description": "Power-on age bucket in years, from smart_9_raw hours divided by 8766 on each drive day: 6 to under 7, 7 to under 8, or 8 or more."
    },
    {
      "name": "model",
      "type": "string",
      "description": "Drive model string as it appears in the daily files, or the ALL row that closes each bucket and equals the sum of its model rows."
    },
    {
      "name": "drives",
      "type": "integer",
      "description": "Distinct serial numbers of the model seen in the bucket between 2025-10-01 and 2025-12-31. A drive that crosses a bucket boundary in the quarter counts in both buckets; the ALL row adds the model rows."
    },
    {
      "name": "drive_days",
      "type": "integer",
      "description": "Daily rows of the model that fell in the bucket. This is the exposure."
    },
    {
      "name": "share_of_bucket_drive_days_percent",
      "type": "number",
      "description": "The model's share of the bucket's drive days, one decimal."
    },
    {
      "name": "failures",
      "type": "integer",
      "description": "Rows with failure = 1 for the model in the bucket."
    },
    {
      "name": "share_of_bucket_failures_percent",
      "type": "number",
      "description": "The model's share of the bucket's failures, one decimal."
    },
    {
      "name": "afr_percent",
      "type": "number",
      "description": "failures / drive_days * 365 * 100, two decimals. Computed here."
    },
    {
      "name": "afr_low95",
      "type": "number",
      "description": "Lower bound of the exact two-sided 95% Poisson (Garwood) interval, in percent."
    },
    {
      "name": "afr_high95",
      "type": "number",
      "description": "Upper bound of the same interval, in percent. Very wide for models with few drive days."
    }
  ],
  "downloadPath": "/data/datasets/backblaze-q4-2025-old-age-by-model.csv",
  "chartPath": "/data/datasets/backblaze-q4-2025-old-age-by-model.svg",
  "citations": [
    {
      "id": "bb-data",
      "title": "Backblaze Hard Drive Test Data, data_Q4_2025.zip (daily files, 92 CSVs)",
      "url": "https://f001.backblazeb2.com/file/Backblaze-Hard-Drive-Data/data_Q4_2025.zip",
      "accessed": "2026-10-10"
    },
    {
      "id": "bb-page",
      "title": "Hard Drive Reliability & Test Data",
      "url": "https://www.backblaze.com/cloud-storage/resources/hard-drive-test-data",
      "accessed": "2026-10-10"
    },
    {
      "id": "garwood-1936",
      "title": "Garwood, F. (1936). Fiducial limits for the Poisson distribution. Biometrika 28(3/4), 437-442",
      "url": "https://doi.org/10.1093/biomet/28.3-4.437",
      "accessed": "2026-10-10"
    },
    {
      "id": "hesela-afr-by-age",
      "title": "Backblaze AFR by drive power-on age, Q4 2025 (the buckets split here)",
      "url": "https://hesela.dev/datasets/backblaze-q4-2025-afr-by-age",
      "accessed": "2026-10-10"
    }
  ]
}