5.32REQUEST SENSE Command (03h)

The REQUEST SENSE command causes the drive to transfer detailed sense data to the initiator. The drive maintains sense data on an individual initiator basis. The data format and field descriptions are shown in Table 5-166and Table 5-167respectively.

Table 5-166REQUEST SENSE Command Descriptor Block-Data Format

Bit

7

6

5

4

 

3

2

1

0

Byte

 

 

 

 

 

 

 

 

 

 

0

 

 

 

Operation

Code (03h)

 

 

 

 

 

 

 

 

 

 

 

 

1 - 3

 

 

 

 

Reserved

 

 

 

 

 

 

 

 

 

 

 

4

 

 

 

Allocation Length

 

 

 

 

 

 

 

 

 

 

 

 

5

 

 

 

 

Control

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 5-167REQUEST SENSE Command Descriptor Block-Field Description

Field

Description

 

 

Allocation Length

The drives can return a maximum of 18 bytes of sense data. The initiator should set

 

this field to the maximum value to receive all the sense data.

5.32.1Sense Data Availability

Sense data is available if the initiator is responsible for an in-progress FORMAT UNIT command (Format Progress Indication is available in the Format Progress Indication Bytes).

The drive returns a sense key of NO SENSE and an additional sense code of NO ADDITIONAL SENSE INFORMATION if it has no sense data available for the initiator.

For Parallel SCSI disk drives, sense data is available if the previous command from the initiator terminated with a CHECK CONDITION status, or if the previous command from the initiator ended with an unexpected BUS FREE error.REQUEST Clearing Sense Data

Sense data is cleared from the drive's memory by one of the following conditions:

•After being returned from a REQUEST SENSE command.

•As soon as any other command is received from the initiator except

INQUIRY.

5-114 Maxtor Atlas 10K V