{
  "slug": "ssd-correlated-failures-nodes-racks",
  "title": "In Alibaba's SSD fleet, 12.9% of failures were in the same node and 18.3% in the same rack within 30 minutes of another failure",
  "kind": "dataset",
  "summary": "Han et al., FAST 2021, studied nearly one million Alibaba SSDs over two years. 12.9% of failures were intra-node and 18.3% intra-rack within 30 minutes, and the strongest SMART attribute had a rank correlation of only 0.23 with them. Cross-check rows come from NetApp (FAST 2020) and Google (OSDI 2010).",
  "license": "Small derived table of figures printed in Han et al. (FAST 2021), Maneas et al. (FAST 2020), and Ford et al. (OSDI 2010), with credit. Not a Creative Commons license. The USENIX papers remain with their authors or publishers. This file is not a copy of the papers and not the data.",
  "licenseUrl": "https://www.usenix.org/system/files/fast21-han.pdf",
  "sourceUrl": "https://www.usenix.org/system/files/fast21-han.pdf",
  "accessed": "2026-10-11",
  "rowCount": 16,
  "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 'nearly' or 'about' it is the stated figure."
    },
    {
      "name": "unit",
      "type": "string",
      "description": "Unit of the value columns: devices, nodes, racks, years, percent, or correlation coefficient."
    },
    {
      "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-correlated-failures-nodes-racks.csv",
  "humanPage": "https://hesela.com/analyses/ssd-correlated-failures-nodes-racks/",
  "limits": [
    "One operator's fleet and ticketing rules.",
    "The 12.9% and 18.3% shares depend on the 30 minute threshold.",
    "88.6% of nodes with two or more SSDs hold one drive model, so some clustering may be a model effect.",
    "The redundancy results come from a trace-driven simulation.",
    "The cross-check rows are other fleets with other definitions."
  ],
  "citations": [
    {
      "id": "han-fast21-pdf",
      "title": "An In-Depth Study of Correlated Failures in Production SSD-Based Data Centers, Han, Lee, Xu, Liu, He, and Liu, USENIX FAST 2021, pages 417 to 429 (USENIX PDF)",
      "url": "https://www.usenix.org/system/files/fast21-han.pdf",
      "accessed": "2026-10-11"
    },
    {
      "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, section 6 on correlated replacements)",
      "url": "https://www.usenix.org/system/files/fast20-maneas.pdf",
      "accessed": "2026-10-11"
    },
    {
      "id": "ford-osdi10-pdf",
      "title": "Availability in Globally Distributed Storage Systems, Ford et al., USENIX OSDI 2010 (USENIX PDF, section 4 on correlated failures)",
      "url": "https://www.usenix.org/legacy/event/osdi10/tech/full_papers/Ford.pdf",
      "accessed": "2026-10-11"
    }
  ]
}