Tandberg Data
Log Sense
13-50
Tandberg SLR Product Line SCSI Functional Specifications
Write Servo Dropout Log Parameters
BYTE
BIT 7
6
5
4
3
2
1
0
n+0
n+1
Parameter Code = 0003h
n+2
DU
DS
TSD
ETC
TMC
R
LP
n+3
Parameter Length = 04h
n+4
Write Servo Dropouts Counter
n+7
Table 13-47: Write Servo Dropout Log Parameters
Parameter Code
The Parameter Code is set to 0003h.
DU
A Disable Update (DU) bit set to 0 indicates that the Drive
is free to update the counter.
A DU bit set to 1 indicates that the Drive shall not update
the counter except in response to a LOG SELECT command that
specifies a new value for the counter.
The initiator may use the LOG SELECT command to set or
clear the DU bit.
The Drive will set the DU bit to 1 when the counter reaches
its maximum value (FFFFFFFFh).
DS
The Disable Save (DS) bit is set to 1 to indicate that the
Drive does not support saving of this log parameter.
(Note: This bit can not be changed by the initiator)
TSD
The Target Save Disable (TSD) bit is set to 1 to indicate
that the Drive does not provide any Drive-defined method
for saving of this log parameter.
(Note: This bit can not be changed by the initiator)
ETC
An Enable Threshold Comparison (ETC) bit indicates whether
comparison to the threshold value is performed or not.
The default value is 0. See the LOG SELECT command for
further description.
TMC
The Threshold Met Criteria (TMC) field is valid only if ETC
bit is 1 and it selects one of four possible Threshold Met
Criteria.
The default value is 11b. See the LOG SELECT command for
further description.
LP
The List Parameters (LP) bit is set to 0 to indicate that
the parameter is a data counter.
(Note: This bit can not be changed by the initiator)
Parameter Length
This field is set to 04h.
Write Servo Dropout
Counter
The Write Servo Dropout Counter is incremented on each two-
channels dropout detection. A dropout may be caused by
physical defect on the tape. The dropout has to be detected
by both read heads, currently used for servo tracking,
simultaneously, to effect Drive operation (and be counted
here).
When a two-channel dropout is detected on a servo track
during write operation, the write current is switched off
to avoid writing over data on neighboring tracks.
