Quantum 1200 Series DAT Autochanger Guia do Utilizador descarregar pdf (Página 153)

SDLT 600 SCSI Interface Guide Chapter 4: SCSI Commands

81-81200-02 REV A01 January 2005 4-111

4.10.2 MODE SENSE Block Descriptor

The following figure describes the MODE SENSE block descriptor that follows the MODE SENSE

header. A description of the MODE SENSE block descriptor is provided in Table 4-62.

Figure 4-62. MODE SENSE Block Descriptor — Data Format

Buffered Mode When set to 0, the drive does not report a GOOD status on WRITE

commands until it actually writes the data blocks to tape.

When set to 1, the drive reports GOOD status on WRITE commands as

soon as the data block has been transferred to the buffer. This is the default

configuration of the drive. Note that if Buffered Mode is not used, the

drive suffers a degradation of performance and capacity.

Speed Always set to 0, indicating the default speed.

Block Descriptor

Length

Specifies the length in bytes of all of the block descriptors. If the DBD bit

in the CDB is set to 0, this value is 8, indicating one Block Descriptor was

sent. If the DBD bit in the CDB is set to 1, this value is 0, indicating no

Block Descriptors were sent.

1. When a VStape I or Super DLTtape I cartridge is mounted in the drive, the MODE SENSE

information reports the Media Type and the correct Density Code as detected on the tape and sets the

Write Protect (WP) bit in the MODE SENSE header to 1. Any command that attempts to write to the

medium (WRITE, WRITE FILEMARKS, ERASE) returns CHECK CONDITION status with Sense

Key set to DATA PROTECT (7) and the Additional Sense Code or Additional Sense Code Qualifier

set to CANNOT WRITE MEDIUM - INCOMPATIBLE FORMAT (30h/05h). The drive does not

update the medium.

Bit

Byte

7 6 5 4 3 2 1 0

0 Density Code

1 – 3

(MSB)

Number of Blocks (000000h)

(LSB)

4 Reserved

5 – 7

(MSB)

Block Length

(LSB)

Table 4-61. MODE SENSE Data Header — Field Descriptions (Continued)

Field Name Description

1 2 ... 148 149 150 151 152 153 154 155 156 157 158 ... 293 294

Sem comentários

Quantum 1200 Series DAT Autochanger Guia do Utilizador Página 153