7. ATAPI Packet Command Specification
MODE SENSE
SONY AIT-2 Turbo drive SDX-560V series Ver.1.0
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The SDX-560V operating in the AIT Format Mode allows tapes to be split into separate and independent
partitions, each with its own Reference, System and Vendor Group areas. The maximum size of a partition may be
the entire tape. A tape partitioned into several partitions may be considered a collection of several separate logical
tapes. This is illustrated below:
Single Partition Tape
BOM
BOT
EOP/EOM
Partition
0
Device Area
System Area
User Data Area
End of Data
|
EOT
Two Partition Tape
BOM BOT
EOP/EOM
Partition 0
Partition 1
Device
Area
System
Area
User Data Area
End of Data
DEV
System
Area
User Data Area
End of
Data
|
EOT
Three Partition Tape
BOM BOT
EOP/EOM
Partition 0
Partition 1
Partition 2
DEV System
Area
User
Data
Area
EOD DEV System
Area
User
Data
Area
EOD DEV System
Area
User
Data
Area
EOD
|
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)
A tape does not require partitioning prior to use. On the first WRITE to a blank tape, the device creates the
System, Reference and Vendor areas before proceeding with the write. In order to reformat media 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:
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 in response to the MODE SENSE command and is set to
03h in order to indicate that the drive is capable of format and partition recognition. This is non-changeable field. It
accepts any values, and always returns 1.
Partition Sizes:
This field allows the host to allocate the capacity for each partition. It will also allow the host to
reallocate the capacity of previously partitioned tapes.
The Partition Size specifies the capacity of all partitions in Megabytes (in the case of SDX-560V-see PSUM field
definition). 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, spanning the whole length of the tape.
The size of Partition 0 is only valid during MODE SENSE and is ignored during MODE SELECT. And remaining
Capacity belongs to Partition 0.
