compare and write in scsi
Send the SCSI COMPARE AND WRITE command to DEVICE. This command receives a data buffer
which contains a verify instance and a write instance each containing num blocks, the
DEVICE will read num blocks starting at logical block address LBA, compare the data read
from the specified blocks to the verify instance and if they match, write the write
instance to the DEVICE at the same logical block address LBA. All of the above operations
shall be performed as an uninterrupted series of actions.
The data buffer which contains the verify and write instances are obtained from the input
file IF, this file is expected to be 2*num blocks long. If bs is not specified, then READ
CAPACITY(10) is used to determine the block size. If not specified, the transfer size will
be the 2*num blocks.
In case of a mismatch between the blocks read from DEVICE and the verify instance in the
data buffer, a check condition will be returned with sense key set to miscompare.
This command is defined in SBC-3 whose most recent revision is 35d. SBC-3 and other SCSI
documents can be found at http://www.t10.org .