Logical Elements Within A Partition - Tandberg Data SLR7-140 PROGRAMMER Manual

Tandberg Data
2.3.4.3. Changing Partition Using the MODE SELECT
Command
The MODE SELECT command can be used to specify the
active partition. The Device Configuration Parameters
Page (page code 10h) is used for this purpose. The
Change Active Partition (CAP) bit must be set to one and
the Active Partition
Partition) or 1 (Directory Partition). The Drive will
then position the tape at the beginning of the specified
partition.
2.4.

Logical Elements Within a Partition

The Recording-Area on a volume may contain two types of
Initiator accessible
marks. These elements
between the Initiator and the medium using READ, WRITE
and WRITE FILEMARKS commands.
A unit of data supplied or requested by the Initiator is
called a logical
according to the specifications of the tape format used
(see [9] - [14]) and may be recorded as one or more
physical blocks on the medium. When the physical block
and the logical block are not recorded in a one-to-one
relationship, it is the responsibility of the device to
perform all blocking,
logical block(s) sent to/from the Initiator.
Filemarks are one kind of tape marks. Filemarks are
special recorded
Initiators traditionally use filemarks to separate user
data from labels and logical groupings of data from each
other.
Setmarks are another kind of tape marks. Setmarks are
special recorded
providing a segmentation scheme hierarchically superior
to filemarks.
Interblock gaps, the gaps between blocks and tapemarks,
are introduced on the medium at the time a block or
tapemark is written
Initiator. Minimum and maximum lengths for interblock
gaps are defined in [9] - [14].
In addition to blocks, tape marks and inter-block gaps,
erase gaps can
automatically recorded
properly terminated. The erase gap acts as an end-of-
data marker on some tape formats.
In addition a single erase gap may be recorded on the
medium through the use of the ERASE command. This erase
gap will cover the whole - or a limited part - of the
medium and the pre-recorded information in the erase gap
will be written over and lost. Refer to section 8 for
further details about the ERASE command.
2-14 Tandberg SLR Product Line SCSI Functional Specifications
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About Tape Streamers
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