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Tandberg Data
27.4.8.
Non-Recoverable Read Error During Space
Forward
If
a
non-recoverable
execution of a SPACE FORWARD command, the bad block will
be
assumed
to
terminate the SPACE command with CHECK CONDITION status.
The Error Code will be set to R
spacing over blocks or tapemarks 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 count and the actual number of blocks or
filemarks and setmarks spaced over (the bad block will
count as one spaced block). When spacing over sequential
tapemarks the VADD bit will be set to zero. When the
command has terminated, the logical tape positions will
be after the bad physical tape block.
When R
EAD RETRIES EXHAUSTED
only accept the following media access commands:
LOAD and REWIND
SPACE with a space code of Space Over Bad Blocks.
READ
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
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.
27.4.9.
Error Condition or Bad Block During Space
Reverse
If a bad block or an error condition is detected during
Space
Reverse
tapemarks), the command terminates with CHECK CONDITION
status.
The
Error
. When spacing over blocks or tapemarks the VADD
EXHAUSTED
bit is set in the Sense Data and the Information Bytes
will hold the residual count. In this case the error or
bad block may have been detected logically in front of
the destination position.
This can happen as the Drive is not able to actually
read in reverse direction. It therefore has to fill the
buffer with data and then test the buffer in reverse
direction. The buffer will then typically also contain
blocks that are logically in front of the destination
position. One of these blocks may be bad and a retry
operation
may
end
.
EXHAUSTED
When spacing over sequential tapemarks the VADD bit will
be set to zero.
Further space operations in the reverse direction are
not allowed after a non-recoverable read error.
27-6
Tandberg SLR Product Line SCSI Functional Specifications
read
error
be
a
data
block
EAD RETRIES EXHAUSTED
has been reported the Drive will
(blocks,
tapemarks
Code
will
be
with
an
Error
Space
occurs
during
and
the
Drive
. When
EAD RETRIES EXHAUSTED
or
sequential
set
to
R
EAD
RETRIES
Code
of
R
EAD
RETRIES
the
will
).
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