Seagate Ultra 320 Incorrect logical unit selection, Sense data, Asynchronous Event Reporting

Note. Some logical units may not detect an overlapped command until after the command descriptor block has been received.

7.6.3Incorrect logical unit selection

The target’s response to an incorrect logical unit identifier is described in the following paragraphs.

The logical unit identifier may be incorrect because:

a.The target does not support the logical unit (e.g., some targets support only one peripheral device). In response to any other command except REQUEST SENSE and INQUIRY, the target shall terminate the command with CHECK CONDITION status. Sense data shall be set to the values specified for the REQUEST SENSE command in item b below;

b.The target supports the logical unit, but the peripheral device is not currently attached to the target. In response to an INQUIRY command the target shall return the INQUIRY data with the peripheral qualifier set to the value required in the SPC-4 standard. In response to a REQUEST SENSE command, the tar- get shall return sense data. The sense key shall be set to ILLEGAL REQUEST and the additional sense code shall be set to Logical Unit Not Supported.

In response to any other command except REQUEST SENSE and INQUIRY, the target shall terminate the command with CHECK CONDITION status. Sense data shall be set to the values specified for the REQUEST SENSE command above;

c.The target supports the logical unit and the peripheral device is attached, but not operational. In response to an INQUIRY command the target shall return the INQUIRY data with the peripheral qualifier set to the value required in Seagate SCSI Command Reference Manual, Part number 100293068. In response to REQUEST SENSE, the target shall return sense data.

The target's response to any command other than INQUIRY and REQUEST SENSE is vendor-specific; or

d.The target supports the logical unit but is incapable of determining if the peripheral device is attached or is not operational when it is not ready.

In response to an INQUIRY command the target shall return the INQUIRY data with the peripheral qualifier set to the value specified in Seagate SCSI Command Reference Manual, Part number 100293068. In response to a REQUEST SENSE command the target shall return the REQUEST SENSE data with a sense key of No Sense unless an auto contingent allegiance exists. The target's response to any other command is vendor-specific.

7.6.4Sense data

Sense data shall be made available by the logical unit in the event a command completes with a CHECK CON- DITION status or other conditions. The format, content and conditions under which sense data shall be pre- pared by the logical unit are specified in this manual, the SPC-4 standard, and other applicable SCSI protocol standards.

Sense data shall be preserved by the logical unit for the initiator until it is transferred by one of the methods listed below or until another task from that initiator is entered into the task set.

The sense data may be transferred to the initiator through any of the following methods:

a.The REQUEST SENSE command specified in Seagate SCSI Command Reference Manual, Part num- ber 100293068;

b.An asynchronous event report; or

c.Autosense delivery.

The following clauses describe the last two transfer methods.

7.6.4.1Asynchronous Event Reporting

Asynchronous Event Reporting is used by a logical unit to signal another device that an asynchronous event has occurred. The mechanism automatically returns sense data associated with the event. Support for asyn- chronous event reporting is a logical unit option.

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