13-1
Tandberg SLR Product Line SCSI Functional Specifications
13.
Log Sense
13.1. Command Description
The LOG SENSE command is used to retrieve statistical
information maintained by the Drive
1
.
The log information consists of numerous counters
related to Drive use and write/read operations to/from
the magnetic tape. When the Log Sense command is issued,
the Drive will return the requested parameter page(s).
Power-on or Hard Reset will set the counters either to
zero or to the last saved value. They are set to the
last saved value only when the counter is identified as
savable (the DS and TSD bits are zero).
The parameter list is transferred during the DATA IN
phase of the command. If the disconnect is allowed, the
Drive will disconnect when executing this command.
13.2. Command Descriptor Block
BYTE
BIT 7
6
5
4
3
2
1
0
00
Operation Code
4Dh
01
Logical Unit Number (LUN)
RESERVED
PPC
SP
02
PC
Page Code
03
RESERVED
04
RESERVED
05
Parameter Pointer
06
07
Allocation Length
08
09
Control Byte
Table 13-1: LOG SENSE Command Descriptor Block
PPC
The parameter Pointer Control (PPC) bit MUST be set to
zero.
SP
If the SP bit is set to 1 the Drive saves
2
all Log
parameters identified as savable by the DS bit (after
performing the specified LOG SENSE operation).
If the Save Parameter (SP) bit is set to 0, the command
is performed and no parameters are saved.
1
Note that the log counter updates are not necessarily synchronized
with the events that they monitor. This means that threshold
comparison can not be used to monitor drive actions with any great
amount of precision.
2
The medium used to store saved log data is specified to handle up to
100000 save operations.
