Rezero Unit Command (01H); Search Data Equal Command (31H); Search Data High Command (30H); Search Data Low Command (32H) - Seagate SCSI Interface Product Manual

SCSI Interface Product Manual, Rev. J
5.37

Rezero Unit command (01h)

The Rezero Unit command (Table 161) requests that the drive set its logical block address to zero and return
the drive read/write heads to the track (or cylinder) containing logical block zero. This command is intended for
systems which disable retries and the initiator performs error recovery. It is longer than a seek to logical block
address zero and should be utilized if seek errors are encountered.
For systems that support disconnection, the drive disconnects when this command is received.
A Rezero Unit command also causes a thermal compensation to occur and resets the thermal compensation
cycle timer back to its start, thus allowing the host to know when to expect the next thermal compensation to
occur. The host can thus prevent critical data transfer operations from being interrupted at an undesirable time.
For drives that support saved log parameters, the Rezero Unit command will also save log counters to the
media and reset the log save timer back to its start.
Table 161: Rezero Unit command (01h)
Bit 7
Byte
0 0
1 0
Logical Unit Number [1]
2 0
3 0
4 0
5 0
Notes.
[1] The Logical Unit Number must be zero.
[2] See "Control byte," paragraph 4.2.6.
5.38

Search Data Equal command (31h)

Not implemented. If received, a Check Condition status is sent.
5.39

Search Data High command (30h)

Not implemented. If received, a Check Condition status is sent.
5.40

Search Data Low command (32h)

Not implemented. If received, a Check Condition status is sent.
6 5
0 0
0 0
0 0
0 0
0 0
0 0
4 3
0 0
0 0
0 0
0 0
0 0
0 0
2 1
0 0
0 0
0 0
0 0
0 0
0 Flag [2] Link [2]
203
0
1
0
0
0
0