{
  "slug": "linnos",
  "term": "LinnOS",
  "aliases": [],
  "definition": "LinnOS is a research operating-system extension that classifies an incoming SSD read as fast or slow to guide admission and replica failover.",
  "note": "The OSDI 2020 prototype learns per workload-device pair from recent completions and pending I/O. A latency-critical read predicted slow is rejected before entering the device queue; the application can retry another replica. Its last-replica attempt bypasses rejection. [hao-osdi20]\n\nThe label is not a drive-failure probability or a latency guarantee. Live completions cannot reveal false revokes because rejected reads never reach that device; the paper evaluates those errors offline. LinnOS+HL additionally uses hedging and must not be confused with the raw classifier. [hao-osdi20]",
  "status": "research",
  "advantages": [],
  "limitations": [
    {
      "text": "Correlated delays, retraining needs and inference overhead limit transfer to other workloads and devices.",
      "citationIds": [
        "hao-osdi20"
      ]
    }
  ],
  "related": [
    "fail-slow",
    "tail-latency",
    "hedged-request",
    "adaptive-replica-selection"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "citations": [
    {
      "id": "hao-osdi20",
      "title": "Hao et al. LinnOS: Predictability on Unpredictable Flash Storage with a Light Neural Network. OSDI 2020, pp. 173-190; sections 3-6.",
      "url": "https://www.usenix.org/system/files/osdi20-hao.pdf",
      "accessed": "2026-11-08"
    }
  ],
  "updated": "2026-11-08"
}