SCSI standalone enclosure services

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SCSI standalone enclosure services is a computer protocol used mainly with disk storage enclosures. It allows a host computer to communicate with the enclosure to access its power, cooling, and other non-data characteristics.

The host computer communicates with one or more SCSI Enclosure Services(SES) controllers in the enclosure via a SCSI interface which may be Parallel SCSI, FC-AL, SAS, or SSA. Each SES controller has a SCSI identity (address) and so can accept direct SCSI commands.

[edit] Supported commands

The following SCSI commands are supported by standalone enclosure services devices:

SCSI command	Operation code	Comment
ACCESS CONTROL IN	86h	Optional
ACCESS CONTROL OUT	87h	Optional
CHANGE ALIASES	A4h	Optional
INQUIRY	12h	Mandatory
LOG SELECT	4Ch	Optional
LOG SENSE	4Dh	Optional
MAINTENANCE IN	A3h	See note 1
MAINTENANCE OUT	A4h	See note 1
MODE SELECT	15h/55h	Optional
MODE SENSE	1Ah/5Ah	Optional
PERISTENT RESERVE IN	5Eh	Optional
PERSISTENT RESERVE OUT	5Fh	Optional
READ BUFFER	3Ch	Optional
RECEIVE DIAGNOSTIC RESULTS	1Ch	Mandatory
REDUNDANCY GROUP IN	BAh	See note 1
REDUNDANCY GROUP OUT	BBh	See note 1
REPORT ALIASES	A3h	Optional
REPORT DEVICE IDENTIFIER	A3h	Optional
REPORT LUNS	A0h	Mandatory
REPORT PRIORITY	A3h	Optional
REPORT SUPPORTED OPERATION CODES	A3h	Optional
REPORT SUPPORTED TASK MANAGEMENT FUNCTIONS	A3h	Optional
REPORT TARGET PORT GROUPS	A3h	Optional
REPORT TIMESTAMP	A3h	Optional
REQUEST SENSE	03h	Mandatory
SEND DIAGNOSTIC	1Dh	Mandatory
SET DEVICE IDENTIFIER	A4h	Optional
SET PRIORITY	A4h	Optional
SET TARGET PORT GROUPS	A4h	Optional
SET TIMESTAMP	A4h	Optional
SPARE IN	BCh	See note 1
SPARE OUT	BDh	See note 1
TEST UNIT READY	00h	Mandatory
VOLUME SET IN	BEh	See note 1
VOLUME SET OUT	BFh	See note 1
WRITE BUFFER	3Bh	Optional

Note 1: The initiator needs to send a SCSI inquiry to interrogate the SCCS bit which says if the SES controller supports this command.