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SCSI Commands

5-34 Quantum DLT 4000 Tape Drive

LOG SELECT Command (4Ch) (continued)

Table 5–16 LOG SELECT Command Descriptor Block - Field Descriptions (continued)

Field Name Description

Parameter List

Length

This field specifies the length, in bytes, of the LOG SELECT parameter list to

be transferred from the initiator to the target during the DATA OUT phase. A

parameter list length of 0 indicates that no data is to be transferred. This

condition is not considered an error.

5.7.1 Log Detection Summary in LOG SELECT Command Descriptor Block

The following conditions constitute errors that are detected by the drive in

relation to the CDB. The request sense data is set to ILLEGAL REQUEST,

INVALID FIELD IN CDB.

The conditions that constitute errors are:

• PCR bit is set to 1 and parameter list is not set to 0.

• SP bit is set to 1

• A parameter list length that would cause a parameter within a valid page to

be truncated or otherwise incompletely initialized.

5.7.2 Operation of LOG SELECT

The LOG SELECT command allows the initiator to modify and initialize

parameters within the logs supported by the tape drive.

There are two ways to initialize the log parameters.

1. Set the PCR bit in the LOG SELECT CDB; this clears all parameters.

2. Specify the log page and parameter values as the log parameters to clear

individual pages. The following pages can be cleared using this method:

Page Code Page Description

02h Write Error Counter Page

03h Read Error Counter Page

32h Compression Ratio Page

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Quantum DLT 4000 Handbuch Seite 134