Sony SDX-800V/R User Manual

 

SONY AIT-3Ex drive SDX-800V series Ver.1.1 

 

6-65 

Operation Code (08h) 

Obsolete Reserved 

SILI 

Fixed 

(MSB)  

 

 Transfer 

Length  

  

(LSB) 

Control 

READ transfers one or more data blocks to the initiator starting with the next block on the drive. 
Fixed: This bit specifies the meaning of the Transfer Length field and whether fixed-length or variable-length blocks 

are to be transferred. 

If the Fixed bit is set to ZERO, Variable Block mode is requested. A single block is transferred with the Transfer 

Length specifying the maximum number of bytes the Host has allocated for the returned data. 

If the Fixed bit is set to one, the Transfer Length specifies the number of blocks to be transferred to the Host. This is 

valid only if the drive is currently operating in Fixed Block mode, in other words, when it has been instructed to use 
fixed-length blocks with  MODE SELECT command. If the Fixed bit is set and the drive is in Variable Block mode, the 

READ is rejected with a CHECK CONDITION status and an ILLEGAL REQUEST sense key set. 

When the Transfer Length is ZERO, no data will be transferred and the current position on the logical unit will not be 

changed. 

A successful READ command with the Fixed bit set transfers (current Block Length) X (Transfer Length) bytes of 

data to the Host. Upon termination of the READ command, the media will be logically positioned after the last block 
transferred (EOM side). 

SILI: A Suppress Incorrect Length Indicator bit of one indicates that the device will not return CHECK CONDITION 

status if the only error is that the Transfer Length is not equal to the actual Block Length recorded on the media. 

Note, however, that if the SILI bit is one and the Fixed bit is ZERO, then the device will report CHECK CONDITION, 

if the requested Transfer Length is less than the actual block size recorded on the medium (over-length condition) 

AND the device is configured to be in Fixed Block mode (i.e. the Block Length field in the MODE SELECT/SENSE 
block descriptor is non-ZERO). 

If the SILI bit is one and the Fixed bit is one, the drive will terminate the command with a CHECK CONDITION status 

with the sense key set to ILLEGAL REQUEST and the additional sense code to ILLEGAL FIELD IN CDB.  If the SILI 

bit is not set and the actual Block Length is different from the specified transfer length, a CHECK CONDITION status 

is returned. Within the Sense data, the Incorrect Length Indicator (ILI) bit and Valid bit will be set to one, the Sense 

Key field is set to NO SENSE and the Information Bytes are to set the difference (residue) between the requested 
Transfer Length and the actual Block Length, or in Fixed Block mode, the difference (residue) between the 

requested number of blocks and the actual number of blocks read. No more than Transfer  Length bytes are 

transferred to the initiator and the tape is logically positioned after the last block transferred (EOM side). 

If the drive reads a File-mark, the drive will return a CHECK CONDITION status. Within the Sense data, the 

File-mark and Valid bits are set and the Sense Key field is set to NO SENSE. The information fields contain the 

residue count. The Additional Sense Code and Additional Sense Code Qualifier fields are set to File-mark Detected. 
Upon termination, the media will be logically positioned after the File-mark (EOM side).  

If, however, the drive encounters a Save-Set Mark during a READ, nothing is reported unless the drive has been 

configured through MODE SELECT to Report Save-Set Marks. The drive will ignore the Set-mark and continue the 

READ. If the Report Save-Set Marks configuration is enabled then the  File-mark and Valid bits are set and the 

Sense Key field is set to NO SENSE. The information fields contain the residue count and the Additional Sense 

Code and Additional Sense Code Qualifier fields are set to Set-mark Detected. The tape is logically positioned after 
the Save-Set Mark (EOM side). 

If the drive detects EOD during the READ, the drive will return a CHECK CONDITION status. Within the Sense data, 

the Valid bit is set and the Sense Key field is set to BLANK CHECK. The information fields contain the residue count. 

The Additional Sense Code and Additional Sense Code Qualifier fields are set to EOD DETECTED. Upon 

termination, the media will be physically positioned before EOD and  after the last block on tape.