182 Product Manual - Disc Drive SCSI-2/SCSI-3 Interface (Vol. 2; Ver. 2), Rev. E
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The Read Long command (see Table 5.2.2-9) requests that the target transfers data to the initiator. The data
passed during the Read Long command shall include the data bytes, followed by the ECC bytes of the single
logical block addressed by the command.
Notes.
[1] In the CDB, the LUN must be zero.
[2] A corrected (CORRECT) bit of zero causes a logical block to be read without any correction made by the
target. A CORRECT bit of one causes the data to be corrected by ECC, if necessary, before being
transferred to the initiator.
[3] A relative address (RelAdr) bit of one indicates that the logical block address field is a two’s complement
displacement. This negative or positive displacement is to be added to the logical block address last
accessed on the logical unit to form the logical block address for this command. This feature is only
available when linking commands. The feature requires that a previous command in the linked group
have accessed a block of data on the logical unit.
A RelAdr bit of zero indicates that the logical block address field specifies the first RelAdr logical block of
the range of logical blocks to be operated on by this command.
[4] The logical block address specifies the logical block at which the read operation shall occur. The most
recent data written in the addressed logical block shall be returned.
[5] The byte transfer length specifies the number of bytes of data that shall be transferred. A transfer length
of zero indicates that no bytes shall be transferred. This condition shall not be considered as an error.
The byte transfer length requested must be equal to the current block size plus all ECC bytes for a data
transfer to occur. If an incorrect number of bytes is stated in the command block, this command termi-
nates with a “Check Condition” status. The correct number of bytes can be determined from the informa-
tion returned in the extended sense data bytes after issuing the Request Sense command. The Request
Sense command shall result in the “Illegal Field In CDB” condition with the “Illegal Request” Sense Key.
The extended sense ILI bit shall be set. The extended sense information bytes contain the difference
(residue) of the requested length minus the actual length in bytes. (Negative values are indicated by
two’s complement notation).
[6] See “Control Byte” paragraph 4.2.6.