
Tandberg Data
Basic Operational Functions
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7-2
Tandberg SLR Reference Manual
7.3. Terminate Write at Physical End Of Tape
During Write Data or Write Filemark, the tape may enter the Physical End Of Tape. The Write
operations must be terminated and the situation must be handled according to the following
procedure:
•
If the tape passes the position denoted as “Logical Early Warning” (LEW), the Drive
will inform the Host by a CHECK CONDITION. The LEW-point is a programmable
position in front of the Early Warning hole on the tape.
The programmed position specifies the amount of data between LEW and EW.
See the description of the Mode Select command for further details about
programming of the LEW-position.
•
At the LEW-position, the Host can be sure that all data transferred to the Drive will be
correctly written to the tape. This position must be regarded as the absolute limit for
normal Write operations.
•
However, the Host may continue to write a few datablocks or Filemarks on the tape.
This termination can consist of specific data blocks or Filemark combinations
containing tape identification, directories etc.
•
At the position between LEW and Physical End Of Tape the Drive will report CHECK
CONDITION and Sense Key = INSUFFICIENT CAPACITY after each Write
command even if the Write command was executed properly.
•
If the Host continues to give Write commands, the Drive will sooner or later reach the
Physical End Of Tape. In this position the Drive will report CHECK CONDITION with
Sense Key = MEDIUM ERROR and no more data can be written.
7.4. Unrecoverable Write Error
If the Drive has tried to rewrite the same block the number of times specified by the Write
Retry Count, without succeeding, the Drive will abort the Write command and send CHECK
CONDITION.
This should be treated as a fatal error situation where either the Drive or the tape-cartridge is
failing due to damage.
7.5. Read Data and Filemarks/Setmarks
A brief overview of the functionality of the Read command will be given in this section. For
more details about error situations and error messages (see Software Manual).
Notice that data and Tapemark (Filemark/Setmark) blocks are written with separate Write
commands. During Read Data, Filemarks are treated as special message blocks, and are
reported with CHECK CONDITION. However, Tapemarks can be read with its own command.
During Read Filemarks, datablocks are not treated as erroneous blocks, but skipped instead.
Despite that Tapemarks are reported with CHECK CONDITION, detection of Filemarks is not
to be regarded as an error situation.