{
  "slug": "tape-end-of-data",
  "term": "Tape end of data (EOD)",
  "aliases": [
    "EOD (tape)",
    "end of recorded data"
  ],
  "definition": "Tape end of data is the logical boundary denoting the end of the recorded user-data sequence on a tape or partition.",
  "note": "In the cited tape-format glossary, EOD is a recorded dataset denoting the end of user data. It differs from a filemark separating logical files and from the medium boundary. The Ultrium sense table distinguishes filemark detection (ASC/ASCQ 00h/01h), EOM (00h/02h) and EOD (00h/05h). Interpret these with the command and sense data, not as interchangeable reports that a tape is full. [ibm-eod] [ibm-sense]\n\nThe Linux SCSI tape driver documents MTEOM as spacing to the end of recorded data despite the ioctl name. Its read interface signals EOD with two consecutive zero-byte reads; end-of-medium early-warning write behavior is documented separately. Those are Linux driver semantics, not a universal API for every tape format. [linux-st]\n\nPractical implication: reaching EOD identifies where the recorded sequence ends. It does not verify that an application produced all intended records, that every preceding record remains readable or that a restore is usable. Compare recovered contents with the expected backup inventory and perform recovery tests. [cisa]",
  "status": "shipping",
  "advantages": [],
  "limitations": [
    {
      "text": "A recorded-data boundary is not a backup-completeness or recoverability guarantee.",
      "citationIds": [
        "ibm-eod",
        "cisa"
      ]
    }
  ],
  "related": [
    "tape",
    "tape-filemark",
    "tape-buffer-synchronization",
    "ltfs",
    "restore-test"
  ],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-25",
  "citations": [
    {
      "id": "linux-st",
      "title": "Linux kernel: SCSI tape driver, block modes, filemarks and EOM behavior",
      "url": "https://docs.kernel.org/scsi/st.html",
      "accessed": "2026-10-18"
    },
    {
      "id": "cisa",
      "title": "CISA, MS-ISAC, NSA and FBI: StopRansomware Guide, offline backups and recovery testing",
      "url": "https://www.cisa.gov/stopransomware/ransomware-guide",
      "accessed": "2026-10-18"
    },
    {
      "id": "ibm-eod",
      "title": "IBM Storage Archive LE 2.4.8: glossary, End of data",
      "url": "https://www.ibm.com/docs/en/storage-archive-le/2.4.8?topic=reference-glossary",
      "accessed": "2026-10-18"
    },
    {
      "id": "ibm-sense",
      "title": "IBM TS2900 Ultrium tape-drive sense data: filemark, EOM and EOD conditions",
      "url": "https://www.ibm.com/docs/en/ts2900tapeautoloader?topic=STCAPQJ%2Fref_3572_appD_drv_sense.htm",
      "accessed": "2026-10-18"
    }
  ],
  "provenance": [
    "Source synthesis of IBM tape definitions and Linux driver behavior; no physical tape experiment was performed."
  ]
}