{
  "slug": "ssd-failures-datacenter-symptoms",
  "title": "38% of failed datacenter SSDs showed none of the four SMART symptoms; the ones that did failed 3 to 20 times as often",
  "kind": "dataset",
  "summary": "Narayanan et al., SYSTOR 2016, studied over half a million SSDs in one operator's datacenters over nearly 3 years. 62% of failed devices had shown at least one of four SMART symptoms and 38% none; devices with a symptom failed 3 to 20 times as often. A classifier reached 87% precision and 71% recall with 5-fold cross-validation. Cross-check rows come from NetApp (FAST 2020) and Backblaze (2016).",
  "license": "Small derived table of figures printed in Narayanan et al. (SYSTOR 2016), Maneas et al. (FAST 2020), and a Backblaze post of 6 October 2016, with credit. Not a Creative Commons license. The ACM and USENIX papers remain with their authors or publishers. This file is not a copy of the papers and not the data.",
  "licenseUrl": "https://bpb-us-e1.wpmucdn.com/sites.psu.edu/dist/9/36635/files/2016/06/systor16_ssd_failures.pdf",
  "sourceUrl": "https://bpb-us-e1.wpmucdn.com/sites.psu.edu/dist/9/36635/files/2016/06/systor16_ssd_failures.pdf",
  "accessed": "2026-10-10",
  "rowCount": 14,
  "columns": [
    {
      "name": "measure",
      "type": "string",
      "description": "The quantity as the source names it."
    },
    {
      "name": "value_low",
      "type": "number",
      "description": "Lower end of a printed range. Empty when the source prints a single value."
    },
    {
      "name": "value_high",
      "type": "number",
      "description": "Single printed value, or the upper end of a range. For 'more than half' it is the stated bound."
    },
    {
      "name": "unit",
      "type": "string",
      "description": "Unit of the value columns: disks, blocks, files, percent of disks, percent of mismatches, or probability."
    },
    {
      "name": "scope",
      "type": "string",
      "description": "Population and window the value applies to."
    },
    {
      "name": "note",
      "type": "string",
      "description": "What the value is not, or the source wording behind it."
    },
    {
      "name": "citation_id",
      "type": "string",
      "description": "Id of the opened source in the citations list."
    }
  ],
  "downloadPath": "/data/datasets/ssd-failures-datacenter-symptoms.csv",
  "humanPage": "https://hesela.com/analyses/ssd-failures-datacenter-symptoms/",
  "limits": [
    "One operator's fleet and workloads; model names are anonymized.",
    "Failure means a fail-stop that takes the server down; about 80% ended in replacement.",
    "Per-model AFR values are in charts, so only printed text figures are used.",
    "The classifier was scored with random 5-fold cross-validation, not a split by time.",
    "The cross-check rows are other fleets with other definitions."
  ],
  "citations": [
    {
      "id": "narayanan-systor16-pdf",
      "title": "SSD Failures in Datacenters: What? When? and Why?, Narayanan et al., SYSTOR 2016 (author PDF, ACM article 7, pages 1 to 11)",
      "url": "https://bpb-us-e1.wpmucdn.com/sites.psu.edu/dist/9/36635/files/2016/06/systor16_ssd_failures.pdf",
      "accessed": "2026-10-10"
    },
    {
      "id": "maneas-fast20-pdf",
      "title": "A Study of SSD Reliability in Large Scale Enterprise Storage Deployments, Maneas, Mahdaviani, Emami, and Schroeder, FAST 2020 (USENIX PDF, pages 137 to 149)",
      "url": "https://www.usenix.org/system/files/fast20-maneas.pdf",
      "accessed": "2026-10-10"
    },
    {
      "id": "backblaze-smart-2016",
      "title": "What SMART Stats Tell Us About Hard Drives, Backblaze, 6 October 2016",
      "url": "https://www.backblaze.com/blog/what-smart-stats-indicate-hard-drive-failures/",
      "accessed": "2026-10-10"
    }
  ]
}