scope:

This standard defines the command set extensions to facilitate operation of SCSI direct-access block devices. The clauses of this standard, implemented in conjunction with the applicable clauses of SPC-3, fully specify the standard command set for SCSI direct-access block devices.

The objective of this standard is to:

a) permit an application client to communicate over a SCSI service delivery subsystem with a logical unit that declares itself to be a direct-access block device in the PERIPHERAL DEVICE TYPE field of the standard INQUIRY data (see SPC-3); and

b) define commands unique to the direct-access block device type.

The set of SCSI standards specifies the interfaces, functions, and operations necessary to ensure interoperability between conforming SCSI implementations.

This standard is a functional description. Conforming implementations may employ any design technique that does not violate interoperability. This standard makes obsolete the following concepts from previous standards:

a) the optical-memory device type, model, commands (the ERASE, MEDIUM SCAN, READ GENERATION, READ UPDATED BLOCK, and UPDATE BLOCK commands), and parameters (Optical-Memory mode page);

b) the write-once device type, model, commands, and parameters;

c) extent reservations and RESERVE/RELEASE reservations;

d) the sequential media model;

e) the rotational position locking model;

f) relative addressing (including the RELADR bit in many CDBs) and the SET LIMITS commands;

g) the CHANGE DEFINITION, COMPARE, COPY, COPY AND VERIFY, LOCK UNLOCK CACHE, RESERVE, RELEASE, REZERO UNIT, SEEK, SEARCH DATA HIGH, SEARCH DATA EQUAL, and SEARCH DATA LOW commands;

h) third-party XOR operation and hybrid XOR operation model, commands (the REBUILD, REGENERATE, and XDWRITE EXTENDED commands), and mode page fields (the XOR Control mode page MAXIMUM REGENERATE SIZE field, MAXIMUM REBUILD TRANSFER SIZE field, and REBUILD DELAY field;

 i) the following mode pages and mode page fields:

A) the Caching mode page NON CACHE SEGMENT SIZE field;

B) the Flexible Disk mode page;

C) the Format Device mode page;

D) the Medium Types Supported mode page and all medium types in the mode parameter header;

E) the Notch and Partition mode page;

F) the following Read-Write Error Recovery mode page fields: the CORRECTION SPAN field, the HEAD OFFSET COUNT field, and the DATA STROBE OFFSET COUNT field;

G) the Rigid Disk Geometry mode page; and

H) the Verify Error Recovery mode page VERIFY CORRECTION SPAN field;

j) the Device Status Output and Device Status Input diagnostic pages;

k) the DISABLE SAVING PARAMETERS (DSP) bit in the FORMAT UNIT parameter list;

l) the INTERLEAVE field in the FORMAT UNIT command; and

m) the erase by-pass (EBP) bit in the WRITE and WRITE AND VERIFY commands. This bit was formerly reserved for the direct-access block device type, so is just marked reserved in this standard