{
  "slug": "backblaze-2026-afr-confidence-intervals",
  "title": "Backblaze model AFR with 95% intervals, Q1 and Q2 2026",
  "kind": "dataset",
  "summary": "Published Q1 and Q2 2026 Backblaze AFRs for 33 hard-drive models, each with an exact 95% Poisson interval computed from the published failures and drive days. Sample: Q1 2026 (January 1 to March 31) 30,203,180 drive days and 1,030 failures; Q2 2026 (April 1 to June 30) 31,553,350 drive days and 1,498 failures. Of 31 models in both quarters, the intervals do not overlap for 4 and overlap for 27. The Poisson assumption is a modelling choice made here, not something Backblaze publishes.",
  "license": "Derivative table transcribed from Backblaze Drive Stats reports for Q1 2026 and Q2 2026. 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 small derived table with computed intervals, not Backblaze's 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/blog/backblaze-drive-stats-for-q2-2026/",
  "accessed": "2026-10-10",
  "rowCount": 33,
  "columns": [
    {
      "name": "mfg",
      "type": "string",
      "description": "Manufacturer label as published by Backblaze."
    },
    {
      "name": "model",
      "type": "string",
      "description": "Drive model identifier as published."
    },
    {
      "name": "size_tb",
      "type": "integer",
      "description": "Nominal capacity in terabytes as published."
    },
    {
      "name": "q1_drive_days",
      "type": "integer",
      "description": "Drive days in Q1 2026 (January 1 to March 31), as published. Empty if the model is not in that table."
    },
    {
      "name": "q1_failures",
      "type": "integer",
      "description": "Failures in Q1 2026 (January 1 to March 31), as published."
    },
    {
      "name": "q1_afr_percent",
      "type": "number",
      "description": "AFR in percent for Q1 2026 (January 1 to March 31), copied as published."
    },
    {
      "name": "q1_afr_low95",
      "type": "number",
      "description": "Lower bound of the exact two-sided 95% Poisson (Garwood) interval for the AFR, in percent, computed here from failures and drive days, Q1 2026 (January 1 to March 31)."
    },
    {
      "name": "q1_afr_high95",
      "type": "number",
      "description": "Upper bound of the same interval, in percent, Q1 2026 (January 1 to March 31)."
    },
    {
      "name": "q2_drive_days",
      "type": "integer",
      "description": "Drive days in Q2 2026 (April 1 to June 30), as published. Empty if the model is not in that table."
    },
    {
      "name": "q2_failures",
      "type": "integer",
      "description": "Failures in Q2 2026 (April 1 to June 30), as published."
    },
    {
      "name": "q2_afr_percent",
      "type": "number",
      "description": "AFR in percent for Q2 2026 (April 1 to June 30), copied as published."
    },
    {
      "name": "q2_afr_low95",
      "type": "number",
      "description": "Lower bound of the exact two-sided 95% Poisson (Garwood) interval for the AFR, in percent, computed here from failures and drive days, Q2 2026 (April 1 to June 30)."
    },
    {
      "name": "q2_afr_high95",
      "type": "number",
      "description": "Upper bound of the same interval, in percent, Q2 2026 (April 1 to June 30)."
    },
    {
      "name": "intervals_overlap",
      "type": "string",
      "description": "yes if the Q1 and Q2 95% intervals share any value, no if they do not. Empty if the model is missing from either quarter. Computed here."
    }
  ],
  "downloadPath": "/data/datasets/backblaze-2026-afr-confidence-intervals.csv",
  "chartPath": "/data/datasets/backblaze-2026-afr-confidence-intervals.svg",
  "citations": [
    {
      "id": "bb-q1-2026-report",
      "title": "Backblaze Drive Stats for Q1 2026",
      "url": "https://www.backblaze.com/blog/backblaze-drive-stats-for-q1-2026/",
      "accessed": "2026-10-09"
    },
    {
      "id": "bb-q2-2026-report",
      "title": "Backblaze Drive Stats for Q2 2026",
      "url": "https://www.backblaze.com/blog/backblaze-drive-stats-for-q2-2026/",
      "accessed": "2026-10-09"
    },
    {
      "id": "bb-drive-stats-data",
      "title": "Hard Drive Reliability & Test Data",
      "url": "https://www.backblaze.com/cloud-storage/resources/hard-drive-test-data",
      "accessed": "2026-10-09"
    },
    {
      "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"
    }
  ]
}