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6.Command Specification
BOM
BOT
System
Device
Area
Area
BOM
BOT
Device
System
User Data Area
Area
Area
The Host may, therefore, partition a tape into one partition which spans the whole physical length of the tape or into
two partitions, each of which will behave as completely separate and independent tapes.
A tape does not require partitioning prior to use. If a Host only wishes to use a single partition tape, then there is no
need to send this page. On the first WRITE to a blank tape, the device will create the System, Reference and Vendor
areas on tape before proceeding with the write. To reformat from a two to a single, or from a single to a two partition
tape, the Host is required to use the Medium Partitions Parameter page.
PSUM: The Partition Size Unit of Measured field defines the units in which the Partition Size value selects the
partition size, which in the case of this drive is Megabytes. Therefore, the drive returns 10b for a MODE SENSE and
will only accept this value for a MODE SELECT, otherwise a CHECK CONDITION status is returned with an
ILLEGAL REQUEST Sense Key set.
Medium Format Recognition: This field is only valid on a MODE SENSE and is set to 03h to indicate that the drive
is capable of format and partition recognition. This is non-changeable field. It accepts all the value, however always
returns 1.
Partition Sizes: This field allows the initiator to allocate the capacity of each partition. It will also allow the initiator to
reallocate the capacity of previously partitioned tapes.
The Partition Size specifies the capacity of all partitions in Megabytes. The drive rounds the Partition Size to the next
whole group value and then applies an algorithm which allows for the writing of ECC-3 frames and for RAW error
recovery so as to reserve sufficient physical space on the media for the specified capacity. The minimum space
allocated shall be 3050 frames.
If the Additional Partitions Defined and Partition Size fields are set to ZERO the drive will initialize the tape as
partition 0, and create a single partitioned tape.
The size of partition 0 is only valid during Mode Sense and is ignored during Mode Select. For Mode Select only
partition 1 size is used when Additional Partitions Defined field is set to 01h. Partition 0 size is ignored. Internally, the
drive computes partition 0 size to be the remaining capacity of the tape. This remaining capacity is the maximum
uncompressed capacity minus partition 1 size.
A second way to issue Mode Select Page 11h is to set Page Length to 08h, and set bytes 8 and 9 to partition 1 size.
In this method partition 0 size is not sent, but this size is still computed as defined above. In either case, Mode Sense
will report partition 0 and partition 1 sizes.
6-44
Single Partition Tape
User Data Area
Two Partition Tape
Partition 1
End of
Data
EOT
BOM = Beginning-of-Media (Physical)
BOT = Beginning-of-Tape (Logical)
EOM = End-of-Media (Physical)
EOP = End-of-Partition (Logical)
EOT = End-of-Tape (Logical)
Figure 6-1: Tape Partition Layout
Partition 0
End of
Data
Partition 0
System
User Data Area
Area
SONY AIT-1 Turbo drive SDX-450V series Ver.1.0
MODE SELECT
EOP/EOM
EOT
EOP/EOM
End of
Data
EOT
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