{
  "slug": "backblaze-2022-2025-afr-by-capacity",
  "title": "Backblaze hard drive AFR by capacity group, 2022 to 2025",
  "kind": "dataset",
  "summary": "Yearly annualized failure rate of Backblaze's hard drives by nominal capacity group, computed from the raw daily Drive Stats files for 2022 to 2025 (sixteen quarterly zips) with the drive-day exposure of each group and exact 95% Poisson intervals. Sample: drives of 3 TB or more, 388,670,883 drive days and 16,051 failures over the four years. In 2025 the 20 to 22 TB group was at 0.51% on 16.0% of drive days, 16 to 18 TB at 1.03%, 12 to 14 TB at 1.84% and 8 to 10 TB at 2.19%. One fleet, and capacity groups mix models and ages, so the file does not show an effect of size.",
  "license": "Derivative table computed from the Backblaze Drive Stats daily files for 2022 to 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 25-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": 25,
  "columns": [
    {
      "name": "year",
      "type": "integer",
      "description": "Calendar year, 2022 to 2025 (all four quarterly files of the year)."
    },
    {
      "name": "capacity_group",
      "type": "string",
      "description": "All hard drives of 3 TB or more, or a nominal capacity group from round(capacity_bytes / 1e12): 3 to 6 TB, 8 to 10 TB, 12 to 14 TB, 16 to 18 TB, 20 to 22 TB, 24 TB and above. A group with no drive days in a year has no row."
    },
    {
      "name": "drive_days",
      "type": "integer",
      "description": "Daily rows (drive days) of the group in the year. This is the exposure."
    },
    {
      "name": "share_of_year_drive_days_percent",
      "type": "number",
      "description": "The group share of the All drive days in that year, one decimal."
    },
    {
      "name": "failures",
      "type": "integer",
      "description": "Rows with failure = 1 in the year."
    },
    {
      "name": "afr_percent",
      "type": "number",
      "description": "failures / drive_days * 365 * 100, two decimals. Computed here, with 365 days in every year."
    },
    {
      "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."
    }
  ],
  "downloadPath": "/data/datasets/backblaze-2022-2025-afr-by-capacity.csv",
  "chartPath": "/data/datasets/backblaze-2022-2025-afr-by-capacity.svg",
  "citations": [
    {
      "id": "bb-data-Q12022",
      "title": "Backblaze Hard Drive Test Data, data_Q1_2022.zip (daily CSV files)",
      "url": "https://f001.backblazeb2.com/file/Backblaze-Hard-Drive-Data/data_Q1_2022.zip",
      "accessed": "2026-10-11"
    },
    {
      "id": "bb-data-Q22022",
      "title": "Backblaze Hard Drive Test Data, data_Q2_2022.zip (daily CSV files)",
      "url": "https://f001.backblazeb2.com/file/Backblaze-Hard-Drive-Data/data_Q2_2022.zip",
      "accessed": "2026-10-11"
    },
    {
      "id": "bb-data-Q32022",
      "title": "Backblaze Hard Drive Test Data, data_Q3_2022.zip (daily CSV files)",
      "url": "https://f001.backblazeb2.com/file/Backblaze-Hard-Drive-Data/data_Q3_2022.zip",
      "accessed": "2026-10-11"
    },
    {
      "id": "bb-data-Q42022",
      "title": "Backblaze Hard Drive Test Data, data_Q4_2022.zip (daily CSV files)",
      "url": "https://f001.backblazeb2.com/file/Backblaze-Hard-Drive-Data/data_Q4_2022.zip",
      "accessed": "2026-10-11"
    },
    {
      "id": "bb-data-Q12023",
      "title": "Backblaze Hard Drive Test Data, data_Q1_2023.zip (daily CSV files)",
      "url": "https://f001.backblazeb2.com/file/Backblaze-Hard-Drive-Data/data_Q1_2023.zip",
      "accessed": "2026-10-11"
    },
    {
      "id": "bb-data-Q22023",
      "title": "Backblaze Hard Drive Test Data, data_Q2_2023.zip (daily CSV files)",
      "url": "https://f001.backblazeb2.com/file/Backblaze-Hard-Drive-Data/data_Q2_2023.zip",
      "accessed": "2026-10-11"
    },
    {
      "id": "bb-data-Q32023",
      "title": "Backblaze Hard Drive Test Data, data_Q3_2023.zip (daily CSV files)",
      "url": "https://f001.backblazeb2.com/file/Backblaze-Hard-Drive-Data/data_Q3_2023.zip",
      "accessed": "2026-10-11"
    },
    {
      "id": "bb-data-Q42023",
      "title": "Backblaze Hard Drive Test Data, data_Q4_2023.zip (daily CSV files)",
      "url": "https://f001.backblazeb2.com/file/Backblaze-Hard-Drive-Data/data_Q4_2023.zip",
      "accessed": "2026-10-11"
    },
    {
      "id": "bb-data-Q12024",
      "title": "Backblaze Hard Drive Test Data, data_Q1_2024.zip (daily CSV files)",
      "url": "https://f001.backblazeb2.com/file/Backblaze-Hard-Drive-Data/data_Q1_2024.zip",
      "accessed": "2026-10-11"
    },
    {
      "id": "bb-data-Q22024",
      "title": "Backblaze Hard Drive Test Data, data_Q2_2024.zip (daily CSV files)",
      "url": "https://f001.backblazeb2.com/file/Backblaze-Hard-Drive-Data/data_Q2_2024.zip",
      "accessed": "2026-10-11"
    },
    {
      "id": "bb-data-Q32024",
      "title": "Backblaze Hard Drive Test Data, data_Q3_2024.zip (daily CSV files)",
      "url": "https://f001.backblazeb2.com/file/Backblaze-Hard-Drive-Data/data_Q3_2024.zip",
      "accessed": "2026-10-11"
    },
    {
      "id": "bb-data-Q42024",
      "title": "Backblaze Hard Drive Test Data, data_Q4_2024.zip (daily CSV files)",
      "url": "https://f001.backblazeb2.com/file/Backblaze-Hard-Drive-Data/data_Q4_2024.zip",
      "accessed": "2026-10-11"
    },
    {
      "id": "bb-data-Q12025",
      "title": "Backblaze Hard Drive Test Data, data_Q1_2025.zip (daily CSV files)",
      "url": "https://f001.backblazeb2.com/file/Backblaze-Hard-Drive-Data/data_Q1_2025.zip",
      "accessed": "2026-10-11"
    },
    {
      "id": "bb-data-Q22025",
      "title": "Backblaze Hard Drive Test Data, data_Q2_2025.zip (daily CSV files)",
      "url": "https://f001.backblazeb2.com/file/Backblaze-Hard-Drive-Data/data_Q2_2025.zip",
      "accessed": "2026-10-11"
    },
    {
      "id": "bb-data-Q32025",
      "title": "Backblaze Hard Drive Test Data, data_Q3_2025.zip (daily CSV files)",
      "url": "https://f001.backblazeb2.com/file/Backblaze-Hard-Drive-Data/data_Q3_2025.zip",
      "accessed": "2026-10-11"
    },
    {
      "id": "bb-data-Q42025",
      "title": "Backblaze Hard Drive Test Data, data_Q4_2025.zip (daily CSV files)",
      "url": "https://f001.backblazeb2.com/file/Backblaze-Hard-Drive-Data/data_Q4_2025.zip",
      "accessed": "2026-10-11"
    },
    {
      "id": "bb-terms",
      "title": "Backblaze Hard Drive Test Data page and use terms",
      "url": "https://www.backblaze.com/cloud-storage/resources/hard-drive-test-data",
      "accessed": "2026-10-11"
    },
    {
      "id": "bb-2025",
      "title": "Backblaze Drive Stats for 2025 (published annual table: 115,638,676 drive days, 4,317 failures, 1.36%)",
      "url": "https://www.backblaze.com/blog/backblaze-drive-stats-for-2025/",
      "accessed": "2026-10-11"
    },
    {
      "id": "garwood",
      "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": "2026-10-11"
    }
  ]
}