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In contrast to the BUSY status condition, the DRIVE NOT READY Sense
Key is returned as part of the Sense data following a REQUEST SENSE
command and indicates that a media access command has been issued
and the medium is not ready to be accessed (for example, the medium is
not installed, the medium has been unloaded, the drive is currently
initializing the medium to prepare it for access).
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Many of the SCSI commands cause data to be transferred between the initiator and
the drive. The content and characteristics of this data are command-dependent.
Table 5–5 lists the information transmitted for all of the commands.
The "Length in CDB" column of Table 5–5 identifies the Command Descriptor
Block field used by the drive to determine how much command-related data are to
be transferred. The units (bytes or logical blocks) for the different Length fields
are implied by the Length Field Name as follows:
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Allocation Length Bytes of data the drive is allowed to send to the initiator
Parameter List Length Bytes of data the initiator has available for the drive
Transfer Length Logical number of data blocks or data bytes the initiator wants
transferred or verified
Byte Transfer Length Bytes of data the initiator wants transferred
The DATA OUT column in Table 5–5 lists the information passed to the drive by
the initiator as part of the command. The DATA IN column lists the information
sent to the initiator by the drive. Numbers in parentheses after an item indicate the
item’s length in bytes. In some cases, additional length information is
communicated during the DATA phase.