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REQUEST SENSE Command (03h) SDLT 600 SCSI Interface Guide

4-216 January 2005 81-81200-02 REV A01

4.27 REQUEST SENSE Command (03h)

The REQUEST SENSE command directs the SDLT tape drive to transfer detailed Sense Data to the

initiator.

Figure 4-120. REQUEST SENSE Command Descriptor Block — Data Format

The Sense Data are valid for a CHECK CONDITION or RESERVATION CONFLICT status returned

on the previous command. The drive preserves the Sense Data bytes until retrieved by a REQUEST

SENSE command or until the receipt of any other command from the same initiator, though some

commands, such as INQUIRY, do not change Sense Data.

If the drive receives an unsolicited REQUEST SENSE, it returns Sense Data with the appropriate

values in the End of Media (EOM), Sense Key, Additional Sense Code, and Additional Sense Code

Qualifier fields. The positional information provided reflects the logical position of the drive. The

drive returns information based on the non-diagnostic data in its buffer as well as the data on the tape

medium. Additionally, bytes 25 through 28 contain the amount of tape to be written in 4 KB blocks.

The REQUEST SENSE command does not cause the drive to flush its buffered data to tape. Therefore,

if the host requires the exact physical positioning of the tape medium, it must precede the REQUEST

Bit

Byte

7 6 5 4 3 2 1 0

0 Operation Code (03h)

1 Reserved DESC

2 – 3 Reserved

4 Allocation Length

5 Control

Table 4-128. REQUEST SENSE Command Data — Field Descriptions

Field Name Description

DESC Descriptor. Indicates which sense data format the drive returns. The drive

does not support descriptor format sense data. Must be set to 0, indicating

that the drive returns fixed format sense data.

Allocation Length Specifies the maximum number of Sense Data bytes to be returned. The

drive terminates the transfer when it has transferred this number of bytes

or all available Sense Data to the host, whichever is less.

SDLT 600

SCSI Interface Guide

SCSI Commands

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Quantum 1200 Series DAT Autochanger Guía de usuario Pagina 258