ISO/IEC 14776-452:2005 PDF

Overview

ISO/IEC 14776-452:2005 - SCSI Primary Commands‑2 (SPC‑2) defines the functional device model and command set for Small Computer System Interface (SCSI) devices. SPC‑2 specifies the mandatory and optional SCSI commands, the request‑response model, and command formats so that a wide range of SCSI devices (disks, tapes, printers, scanners, etc.) can interoperate across different transports and implementations. The SCSI protocol described supports peer‑to‑peer I/O over bus widths (8 or 16) and both asynchronous and synchronous transfer modes.

Key Topics

• Device model and interoperability: functional description applicable to all SCSI device types; design freedom allowed as long as interoperability is preserved.
• Request‑response model & Command Descriptor Block (CDB): structure and usage of fixed and variable length CDBs, common fields (operation code, service action, LBA, transfer length, etc.).
• Mandatory and optional commands: core commands implemented by all device servers (e.g., INQUIRY, REQUEST SENSE, TEST UNIT READY).
• Command suites and examples: detailed behavior for commands such as INQUIRY, EXTENDED COPY, MODE SENSE/MODE SELECT, LOG SENSE/LOG SELECT, and PERSISTENT RESERVE IN.
• Data transfer and media types: support for block and sequential devices, stream operations, inline/embedded data descriptors.
• Reservations and persistent reservations: Reserve/Release and Persistent Reservation methods, registration, preemption, and preservation across events.
• Self‑test and error handling: default, short and extended self‑tests, foreground/background modes, and procedures for error detection and task management.
• Multi‑port/multi‑initiator behavior: rules for devices with multiple ports or initiators; parameter rounding and other device characteristics.

Applications

ISO/IEC 14776‑452:2005 (SPC‑2) is essential for:

• Storage device manufacturers implementing firmware for disks, tapes, and other SCSI peripherals.
• Operating system and driver developers building SCSI stacks and device drivers that must conform to command semantics and CDB formats.
• SAN and storage integrators ensuring interoperability across heterogeneous devices and transports (parallel SCSI, Fibre Channel, etc.).
• QA, certification and test labs validating compliance with SCSI command behavior and reservation semantics.
• Storage management and backup software that uses advanced commands (EXTENDED COPY, persistent reservations) for cloning, replication, and coordination.

Keywords: ISO/IEC 14776‑452, SPC‑2, SCSI Primary Commands, SCSI commands, Command Descriptor Block, persistent reservations, INQUIRY, EXTENDED COPY, SCSI interoperability.

Related Standards

Related documents include other parts of the ISO/IEC 14776 SCSI series and complementary transport specifications (SCSI Parallel Interface, Fibre Channel SCSI transport). These define transport bindings, hardware signaling, and newer command sets (e.g., later SPC revisions) that work with the SPC‑2 functional model.