Overview - ISO/IEC 15307:1997 (DLT 4)
ISO/IEC 15307:1997 defines the physical, magnetic and logical recording characteristics for 12.7 mm, 128-track magnetic tape cartridges using the Digital Linear Tape 4 (DLT 4) format. The standard enables vendor-neutral data interchange by specifying cartridge dimensions, magnetic properties, recording method and a tape file/record format. It was prepared by ECMA as ECMA‑231 and adopted by ISO/IEC JTC 1.
Key facts from the standard:
- Media: 12.7 mm (0.5 in) wide, 128-track magnetic tape cartridge
- Typical capacity: 20 Gbytes uncompressed (about 40 Gbytes compressed)
- Tape length: 557 m ± 5 m; width specified as 12.649 mm ± 0.010 mm
- Defines the DLT 4 logical and physical format, CRC/ECC schemes and calibration areas
Key topics and technical requirements
ISO/IEC 15307 covers technical areas essential to reliable interchange:
- Physical and mechanical specs: cartridge case, tape leader, reel, moments of inertia and material requirements.
- Unrecorded tape properties: base film, magnetic and back coatings, thickness, roughness, adhesion, friction and abrasivity.
- Magnetic recording characteristics: physical recording density (e.g., 2 142 ftpmm referenced), signal amplitude, overwrite, peak shift and flux transition spacing.
- Tape format and layout: Reference Edge, calibration/guard areas, directory area, data area, physical vs. logical tracks, and track widths.
- Data format and error handling: byte/bit ordering (8-bit bytes), Logical/Physical Blocks, preamble/sync/data/EDC/CRC/ECC structure, CRC character (64-bit) and ECC generation.
- Environment, safety and handling: test and operating conditions (e.g., testing at 23 °C ±2 °C, RH 40–60%), operating range (10–40 °C, RH 20–80%), storage and archival recommendations, stray magnetic field limits and flammability/safety requirements.
- Conformance rules: requirements for cartridge manufacturers, generating systems and receiving systems to claim conformance.
Practical applications and users
ISO/IEC 15307 is used where cross-vendor compatibility and long-term data interchange are required:
- Tape media manufacturers and cartridge designers (to meet interchange specs)
- Tape drive and recorder manufacturers (to support DLT 4 read/write and calibration)
- Data centers, backup/archive operators and libraries (for reliable archival interchange)
- QA and test laboratories (to verify tape quality, signal amplitude, ECC/CRC and environmental behavior)
- System integrators implementing backup/restore workflows and long-term preservation strategies
Related standards
- ECMA-231 (origin of the specification)
- ISO 1001:1986 (magnetic tape labelling - referenced for labelling interoperability)
Keywords: ISO/IEC 15307, DLT 4, magnetic tape cartridge, 12.7 mm, 128-track, data interchange, tape format, CRC, ECC, tape storage, archival backup.