Information technology — Small Computer System Interface (SCSI) — Part 454: SCSI Primary Commands — 4 (SPC-4) (Adopted ISO/IEC 14776-454:2018, first edition, 2018-04)
Standards development within the Information Technology sector is harmonized with international standards development. Through the CSA Technical Committee on Information Technology (TCIT), Canadians serve as the SCC Mirror Committee (SMC) on ISO/IEC Joint Technical Committee 1 on Information Technology (ISO/IEC JTC1) for the Standards Council of Canada (SCC), the ISO member body for Canada and sponsor of the Canadian National Committee of the IEC. Also, as a member of the International Telecommunication Union (ITU), Canada participates in the International Telegraph and Telephone Consultative Committee (ITU-T).
This Standard has been formally approved, without modification, by the Technical Committee and has been developed in compliance with Standards Council of Canada requirements for National Standards of Canada. It has been published as a National Standard of Canada by CSA Group.
ISO/IEC 14776 (all parts) provides for many different types of SCSI devices (e.g., disks, tapes, media changers). This standard defines a device model that is applicable to all SCSI devices. Other command standards expand on the general SCSI device model in ways appropriate to specific types of SCSI devices.
ISO/IEC 14776 (all parts) specifies the interfaces, functions, and operations necessary to ensure interoperability between conforming SCSI implementations. This standard is a functional description. Conforming implementations employ any design technique that does not violate interoperability.
This standard defines the SCSI commands that are mandatory and optional for all SCSI devices. Support for any feature defined in this standard is optional unless otherwise stated. This standard also defines the SCSI commands that may apply to any device model.
The following commands, parameter data, and features defined in previous versions of the SPC standard are made obsolete by this standard:
a) the TARGET RESET supported (TRS) bit and the WAKEUP supported (WAKES) bit in the REPORT SUPPORTED TASK MANAGEMENT FUNCTIONS parameter data;
b) code value 10b (i.e., Per initiator port) in the MODE PAGE POLICY field in the mode page policy descriptor in the Mode Page Policy VPD page;
c) the removable medium devices with an attached medium changer model, MCHNGR bit in the standard INQUIRY data, the MOVE MEDIUM ATTACHED command in disks and tapes, and the READ ELEMENT STATUS ATTACHED command in disks and tapes;
d) linked commands;
e) the PPC bit in the LOG SENSE command;
f) the NUL bit in EXTENDED COPY command target descriptors (i.e., CSCD descriptors in this standard);
g) EXTENDED COPY support for the processing of setmarks by sequential-access devices;
h) READ BUFFER commands with the MODE field set to 00h and 1Ah; and
i) WRITE BUFFER commands with the MODE field set to 00h, 1Ah, and 1Bh.