{
  "slug": "scsi-deferred-error",
  "term": "SCSI deferred error",
  "aliases": [
    "deferred sense",
    "deferred CHECK CONDITION"
  ],
  "definition": "A SCSI deferred error reports a failure of previously acknowledged work through a later eligible command.",
  "note": "Buffered writes and immediate operations can return GOOD before their underlying work finishes. A later report must therefore be distinguished from an error of the command receiving it. Preserve autosense with its original status rather than assuming a later REQUEST SENSE will reproduce it. [ibm-3592]\n\nLinux v6.12 recognizes fixed-format response codes 70h/71h and descriptor-format codes 72h/73h as current/deferred pairs. The sense key alone does not encode this distinction. The Information field additionally needs validity and command-specific interpretation. [linux-st-code]\n\nA nonzero printed Information number alone does not establish a residual. Hesela's ten synthetic decoder inputs exercise timing, format and validity independently. All returned decoder status zero, including eight Medium Error inputs: this is an offline decoding result, not successful tape I/O. [ibm-3592] [hesela-decoder]",
  "related": [
    "scsi-sense-key",
    "tape-buffer-synchronization",
    "tape-early-warning"
  ],
  "status": "shipping",
  "advantages": [],
  "limitations": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-21",
  "provenance": [
    "Autosense clearing and deferred-command eligibility are described for IBM 3592 in sections 4.14.2-4.14.3. [ibm-3592]",
    "IBM 3592 section 6.8.2 describes Information as generally valid only for non-deferred errors; the synthetic decoder inputs are not claimed to be drive-emitted records. [ibm-3592] [hesela-decoder]"
  ],
  "citations": [
    {
      "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"
    },
    {
      "id": "linux-st-code",
      "title": "Linux v6.12 st_analyze_sense: response format, deferred flag and information validity",
      "url": "https://github.com/torvalds/linux/blob/v6.12/drivers/scsi/st.c#L297",
      "accessed": "2026-10-21"
    },
    {
      "id": "hesela-decoder",
      "title": "Hesela: ten offline synthetic sg_decode_sense observations, exact bytes, outputs and hashes",
      "url": "https://hesela.com/research/tape-eom/observation.json",
      "accessed": "2026-10-21"
    }
  ]
}