Table of Contents
Advertisement
Page 120
WRITE
Command Descriptor Block
Field Descriptions
The Write command transfers one or more data blocks from the Initiator to the drive.
If the Transfer Length is zero, no data is transferred, and the current position of the
tape is not changed. This condition is not considered an error.
Bits
Byte
7
6
0
1
Ignored LUN
2
3
4
5
Field
Bytes
Bits
Operation
0
Code
Ignored
1
5-7
Logical
Unit
Fixed
1
0
Transfer
2-4
Length
Reserved
Control
5
If the Fixed flag is clear, the initiator will transfer a single block of the length indicated
in Transfer Length.
If the Fixed flag is set, the initiator will transfer a sequence of blocks. The Transfer
Length field gives the number of blocks. The current fixed block length gives the
length of the blocks.
At Early Warning, the drive completes the current block transfer and terminates the
command with a Check Condition, EOM bit set, and Sense Key equal to 0. If the
SEW bit (in Mode Select Device Configuration Page) is set, the data in the buffer is
then written to tape.
Subsequent Write commands complete with a Check Condition and the EOM bit set.
If writing the buffer to tape is unsuccessful because of EOT, a Volume Overflow is
reported. The Residual count field in the Request Sense data reports the amount of
data not transferred. Writing can continue in the Early Warning region until EOT is
5
4
3
Operation Code (0Ah)
Reserved
Transfer Length, MSB
Transfer Length
Transfer Length, LSB
Control
Description
The Operation Code for Write is 0Ah.
The LUN field is residual from the SCSI-1 days and is ignored.
0 = Variable block length. Transfer Length contains the number of
bytes to write.
1 = Fixed block length, as specified by the MODE SELECT Block
Descriptor. Transfer Length contains the number of blocks to
write.
This field specifies the number of bytes (Fixed = 0) or blocks (Fixed
= 1) to be written. A transfer length of 0 is valid and no data is writ-
ten.
All reserved bits must be 0.
The control field must be 0.
LTO SCSI Interface Manual
2
1
0
Fixed
Advertisement
Table of Contents
