Overview
ISO/IEC 12247:1993 specifies a standardized 3.81 mm wide magnetic tape cartridge format for information interchange using helical-scan recording - the Digital Data Storage (DDS) format for 60 m and 90 m tapes. The standard defines the physical and magnetic characteristics of the cartridge and tape, the required quality of recorded signals, the recorded format and the recording method so that cartridges can be interchanged reliably between different drives and systems.
Key topics and technical requirements
- Cartridge types: Defines two cartridge types - Type A (magnetic tape nominal thickness 13 µm, intended for the shorter tape length) and Type B (nominal thickness 9 µm, for longer tape lengths).
- Physical and mechanical specs: Detailed requirements for the cartridge case, lid, hubs, detection holes, support/datum areas and dimensional tolerances to ensure mechanical interoperability with drives.
- Unrecorded tape properties: Material, tape width, total thickness, coating and layer adhesion, curvature, tensile strength and residual elongation requirements.
- Magnetic recording characteristics: Specifies optimum recording field, signal amplitude, overwrite behavior, physical recording densities and signal-to-noise expectations to guarantee read/write compatibility.
- Format and layout: Defines the on-tape format (Basic Groups, Sub‑Groups, Main Data Blocks, housekeeping frames), track geometry (azimuths, track pitch, track width), device/system/data areas, partitioning and End‑Of‑Data/Early‑Warning points.
- Conformance rules: Criteria for cartridge, generating-system and receiving-system conformance, including optional features (Media Recognition System - MRS, Read‑After‑Write, multiple representations, ECC3 frames). Conformance claims must state supported cartridge types and optional features.
- Measurement and test methods: Annexes provide standardized test procedures (light transmittance, S/N measurement, bit shift, track edge linearity, read‑after‑write, transport recommendations, etc.).
Applications and who uses it
- Tape drive manufacturers: ensure mechanical, magnetic and format compatibility across drives.
- Media manufacturers: produce cartridges and tapes meeting physical and magnetic requirements for interchangeability.
- Data centers & archival storage: implement reliable long-term tape backup and migration strategies using standardized DDS cartridges.
- System integrators and test labs: validate conformance, perform signal and mechanical testing, and certify media/drive interoperability.
- Forensics and data exchange: enable trusted transfer of archived data between organizations and vendors.
Related standards
Keywords: ISO/IEC 12247, DDS format, 3.81 mm magnetic tape, helical scan recording, tape cartridge standard, Type A, Type B, data interchange, tape drive interoperability.