Commands106
READ 08h
READ transfers zero or more data blocks to the host starting at the current logical position.
Pre-execution checks:
If both the SILI and Fixed bits are set, CHECK CONDITION status is reported. Sense data is as
described in the Illegal Field Checks. The field pointers indicate the Fixed bit field.
NOTE: Transfers of 4 bytes or less are not supported.
Command descriptor block:
CDB fields:
If the Fixed flag is clear and Transfer Length is not zero, then a single block of the length in
Transfer Length is to be transferred. If the next block on tape is of this length or shorter it is
transferred to the initiator. If the next block is longer than this length, 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,
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,
Check Condition
status is returned, ILI will be reported as described below. If the length of the block was not the
same as in Transfer Length and the Suppress Illegal Length Indicator (SILI) flag was set,
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, a sequence of blocks of the currently configured block length is to be
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
long and
Check Condition status (ILI will be reported as described below). If a block that is shorter
than the configured length is encountered before the sequence is complete, the blocks up to that
block are returned followed by all of that block and
Check Condition status (ILI will be reported as
Illegal Field Fixed Bit Reservation Deferred Error
Unit Attention Media Access Diagnostic Status
7 6 5 4 3 2 1 0
0 Operation Code (08h)
1 Reserved(0) SILI Fixed
2 (MSB)
Transfer Length
4 (LSB)
5 Control
