{
  "slug": "silent-corruption-checksum-mismatches",
  "title": "0.86% of nearline disks and 0.065% of enterprise disks developed a checksum mismatch in 41 months",
  "kind": "dataset",
  "summary": "Bairavasundaram et al., FAST 2008, report that 3,088 of about 358,000 nearline disks (0.86%) and 767 of 1.17 million enterprise-class disks (0.065%) developed at least one silent checksum mismatch in 41 months of support logs covering 1.53 million disks, about 400,000 mismatched 4 KB blocks in all. The median affected disk had 3 mismatches, the mean 104, the maximum 33,000. Only detected corruption is counted. A CERN IT report from 2007 gives an independent but different measure: 22 of 33,700 files failed a checksum comparison.",
  "license": "Small derived table of figures printed in Bairavasundaram et al. (FAST 2008) and the CERN IT report Data integrity (Panzer-Steindel, draft 1.3, 2007), with credit. Not a Creative Commons license. The USENIX proceedings state that rights to individual papers remain with the author or the author's employer. This file is not a copy of either document and not the underlying support logs or probe data.",
  "licenseUrl": "https://www.usenix.org/legacy/events/fast08/tech/full_papers/bairavasundaram/bairavasundaram_html/index.html",
  "sourceUrl": "https://www.usenix.org/legacy/events/fast08/tech/full_papers/bairavasundaram/bairavasundaram_html/index.html",
  "accessed": "2026-10-10",
  "rowCount": 18,
  "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/silent-corruption-checksum-mismatches.csv",
  "humanPage": "https://hesela.com/analyses/silent-corruption-checksum-mismatches/",
  "limits": [
    "Only corruption the storage system detected is counted. Corruption that is never read or scrubbed is invisible.",
    "Logging is optional for customers and removed disks are counted only until removal.",
    "A disk's result includes its adapter and shelf path. The paper names faulty adapters or shelf controllers for three models.",
    "The paper prints a mean of 104 for the whole sample and 78 in the first-17-months analysis.",
    "The CERN report is a 2007 internal draft from one site with its own probes. Its counts are not per-disk shares and do not test the NetApp percentages.",
    "Several results appear only as charts in the paper and are not in this file."
  ],
  "citations": [
    { "id": "bairavasundaram-usenix-html", "title": "An Analysis of Data Corruption in the Storage Stack, Bairavasundaram et al., FAST 2008 (USENIX HTML proceedings)", "url": "https://www.usenix.org/legacy/events/fast08/tech/full_papers/bairavasundaram/bairavasundaram_html/index.html", "accessed": "2026-10-10" },
    { "id": "bairavasundaram-usenix-pdf", "title": "An Analysis of Data Corruption in the Storage Stack (USENIX PDF, used for numerals the HTML conversion drops)", "url": "https://www.usenix.org/legacy/events/fast08/tech/full_papers/bairavasundaram/bairavasundaram.pdf", "accessed": "2026-10-10" },
    { "id": "cern-data-integrity-2007", "title": "Data integrity, Bernd Panzer-Steindel, CERN IT, draft 1.3, 8 April 2007", "url": "https://indico.cern.ch/event/13797/contributions/1362288/attachments/115080/163419/Data_integrity_v3.pdf", "accessed": "2026-10-10" }
  ]
}