Table of Contents
Advertisement
Page 74
Field Descriptions
Field
Bytes
Bits
Operation
0
Code
Ignored
1
5-7
Logical
Unit
SILI
1
1
Fixed
1
0
Transfer
2-4
Length
Reserved
Control
5
If the SILI bit is 1 and the Fixed bit is 1, the drive returns a Check Condition with
Illegal Request sense key with an additional sense code of Invalid Field in CDB.
When the SILI bit is 1 and Fixed bit is 0 and the only error encountered by the drive
is that the actual block length differs from the requested transfer length, then the
drive:
•
Returns a Check Condition if the actual block length is larger than the requested
transfer length and the Block Length field in the Mode Parameter block
descriptor is nonzero.
•
Does not return a Check Condition if the actual block length is smaller than the
requested transfer length or if the actual block is larger than the requested block
and the block length in the Mode Parameter block descriptor is 0.
If the Fixed flag is clear and Transfer Length is not zero, then a single block of the
length in Transfer Length is transferred. If the next block on tape is of this length or
shorter then it is transferred to the initiator. If the next block is longer than this length,
then only the length requested is returned and the logical position is set to after the
record. If the length of the block was the same as the Transfer Length field, then
good status is returned. If the length of the block was not the same as in Transfer
Length and the Suppress Illegal Length Indicator (SILI) flag was clear, then Check
Condition Status is returned. If the length of the block was not the same as in
Transfer Length and the Suppress Illegal Length Indicator (SILI) flag was set, then
Good status is returned.
If the fixed flag is set and the Transfer Length field is not zero and the Suppress
Illegal Length Indicator (SILI) flag is clear, then a sequence of blocks of the currently
configured block length is returned, the number of blocks being indicated in the
Transfer Length field. If there is a sequence of blocks of this length on the tape, they
are returned to the initiator with good status. If a block that is longer than the
configured length is encountered before the sequence is complete, the blocks up to
that block are returned followed by the configured length from the record that was too
Description
The Operation Code for Read is 08h.
The LUN field is residual from the SCSI-1 days and is ignored.
0 = Return Check Status when an incorrect block length is de-
tected.
1 = Suppresses incorrect length error reporting when reading vari-
able-length blocks
0 = Variable block length. Transfer Length contains the number of
bytes to return.
1 = Fixed block length, as specified by the Mode Select Block De-
scriptor. Transfer Length contains the number of blocks to re-
turn
This field specifies the number of bytes (Fixed = 0) or blocks (Fixed
= 1) to be read. A transfer length of 0 is valid and no data is trans-
ferred.
All reserved bits must be 0.
See Control Byte Format on page 18.
LTO SCSI Interface Manual
Advertisement
Table of Contents
