{
  "slug": "tape-early-warning",
  "term": "Tape early warning",
  "aliases": [
    "end-of-medium early warning"
  ],
  "definition": "Tape early warning signals that a write is approaching the usable end of a tape partition before all remaining recording space is exhausted.",
  "note": "Linux v6.12 describes a write completing at early warning, followed by ENOSPC, then another permitted write so an application can finish its trailer. Successful writes and ENOSPC alternate until physical exhaustion or another error. This is driver-specific behavior, not a universal retry rule. [linux-st]\n\nProgrammable early warning adds advance notice before the ordinary warning boundary. Crossing that configured zone does not itself synchronize buffered data. A warning does not establish the remaining application payload capacity. [ibm-3592]",
  "related": [
    "tape",
    "tape-buffer-synchronization",
    "scsi-deferred-error"
  ],
  "status": "shipping",
  "advantages": [],
  "limitations": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-21",
  "provenance": [
    "The programmable-zone description is scoped to IBM 3592 GA32-0968-07 section 4.7, not every LTO drive. [ibm-3592]",
    "Documented behavior and source review, not a measured end-of-medium experiment."
  ],
  "citations": [
    {
      "id": "linux-st",
      "title": "Linux v6.12: SCSI tape driver, EOM behaviour when writing",
      "url": "https://github.com/torvalds/linux/blob/v6.12/Documentation/scsi/st.rst#L287",
      "accessed": "2026-10-21"
    },
    {
      "id": "ibm-3592",
      "title": "IBM 3592 SCSI Reference GA32-0968-07 (2026), sections 4.7, 4.14 and 6.8.2",
      "url": "https://www.ibm.com/support/pages/system/files/inline-files/3592%20SCSI%20Reference_GA32-0968-07.pdf#page=78",
      "accessed": "2026-10-21"
    }
  ]
}