Quantum 10K II - Manual (Page 290)

SCSI Description
Quantum Atlas 10K II Ultra160/m SCSI Hard Disk Drives 5–223
5.50 WRITE LONG Command (3Fh)
The WRITE LONG and READ LONG commands allow the initiator to issue raw
reads and writes of physical sectors addressed as logical blocks with an assumed
sector length of 512 bytes. These commands are used to verify the correction
capability of the drive's ECC and to create defects of a known kind and location to
verify the drive's recovery and bad sector handling policies.
Bit
Byte
7 6 5 4 3 2 1 0
0 Operation Code (3Fh)
1 Reserved RelAdr
2 - 5 Logical Block Address
6 Reserved
7 - 8 Byte Transfer Length (562)
9 Control
Figure 5–110 WRITE LONG Command Descriptor Block — Data Format
Table 5–104 WRITE LONG Command — Field Descriptions
Field Description
RelAdr Relative Address. This drive does not support this feature; the field must be
0.
Logical Block Address The address of the first logical sector where the Write operation will occur.
Byte Transfer Length Must be 562. This value reflects the number of bytes spanned by the ECC,
including the ECC itself, rounded up to the next word (this is easiest
understood in bits: 4096 data bits + 1 force error bit + 15 Logical Block
Address bits + 16 cross check bits + 2 pad bits + 360 ECC bits + 6 pad
bits that are not written to media but are only needed for transfer = 4496
bits or 562 bytes). Any other value in this field results in a CHECK
CONDITION status and the appropriate sense data.
The initiator should first issue a READ LONG, then modify the data portion
only, and then issue a WRITE LONG. It is also recommended that the drive
be reformatted after these commands are used.
If the drive is configured with a sector size other than 512 bytes per sector,
the WRITE LONG command affects the first 512 byte sector set aside by the
drive for the given Logical Block Address.