Tandberg Data
Read
17-8
Tandberg SLR Product Line SCSI Functional Specifications
When the Drive receives a new READ command the Drive
will execute a Space Over Bad Blocks operation to move
the logical tape position until it can safely detect the
beginning of a logical block. This READ command will not
transfer any data and it will be terminated with another
CHECK CONDITION status (indicating R
EAD RETRIES EXHAUSTED
).
Yet another READ command will start transferring data
from this logical block.
If there are more non-recoverable errors in the next
logical block also, good data is again transferred up to
the first error, CHECK CONDITION is reported and the
whole process described above is repeated.
17.3.8. Illegal Termination
When the Drive can see no more data on a tape, it always
checks that the last block is followed by an end-of-data
marker before reporting End Of Data (Blank Check). If
the end-of-data marker is not found, the READ command is
terminated with CHECK CONDITION status. The Error Code
will be set to R
EAD RETRIES EXHAUSTED
. The Valid (VADD) bit
in the sense data list will be set to one. The
Information Bytes will be set to the difference
(residue) between the requested Transfer Length and the
actual transfer length. It will not be possible to
continue the Read operation.
When a variable length block has been truncated due to
an Illegal Termination error, Illegal Length is not
signaled. Instead the Illegal Termination error takes
priority and the Error Code is set to R
EAD RETRIES
EXHAUSTED
.
17.3.9. Read After Write
If a READ command is issued when the Drive is in WRITE
mode (i.e. immediately after a write operation, see
section 4.5. Command Sequencing for details), the Drive
will terminate the READ command immediately with CHECK
CONDITION status. The Error Code is set to either E
ND
-
OF
-
DATA DETECTED
or E
ND
-
OF
-
DATA DETECTED AFTER
LEW depending on
whether the tape is positioned before or after LEW. The
Drive continues to be in WRITE mode.
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