{
  "slug": "d-sptf",
  "term": "D-SPTF",
  "aliases": [
    "Distributed Shortest-Positioning Time First"
  ],
  "definition": "D-SPTF is a decentralized storage protocol that coordinates replicated read queues using cache hits and predicted disk positioning times.",
  "note": "A cache miss is forwarded to replica holders. Claims remove competing queued reads; concurrent bids prefer shorter positioning time, then lower brick ID. Pre-scheduling provides a short coordination window. [dsptf]\n\nDelayed or lost claims can still cause duplicate work. A claimant that fails before replying requires client timeout and retry. This is not an exactly-once guarantee. [dsptf]\n\nThe ASPLOS 2004 evaluation uses DiskSim, not a deployed fleet. Modern SSD performance is not established. [dsptf]",
  "status": "research",
  "advantages": [],
  "limitations": [],
  "related": [
    "adaptive-replica-selection",
    "tied-request",
    "seek-time",
    "io-scheduler"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "citations": [
    {
      "id": "dsptf",
      "title": "Lumb, Golding and Ganger. D-SPTF: Decentralized Request Distribution in Brick-based Storage Systems. ASPLOS 2004, sections 3-5.",
      "url": "https://www.pdl.cmu.edu/PDL-FTP/SelfStar/dsptf-asplos04.pdf",
      "accessed": "2026-11-09"
    }
  ],
  "updated": "2026-11-09",
  "provenance": [
    "Primary-paper review; no simulator rerun or hardware experiment."
  ]
}