Page
42
LTO SCSI Interface Manual
LOG SENSE
The Log Select and Log Sense commands work in conjunction to allow the host to
control and obtain statistical information about cartridge usage and error rates. This
information consists of counters of particular events.
Log Sense data is obtained by specifying a log page in the Page Code field of the
Log Sense CDB. The host can request only one page of data with each Log Sense
command. The available pages are found by reading the Supported Log Pages Log
(00h).
Command Descriptor Block
Byte
Bits
7
6
5
4
3
2
1
0
0
Operation Code (4Dh)
1
Ignored LUN Reserved
2
PC
Page Code
3
Reserved
4
Reserved
5
Parameter Pointer, MSB
6
Parameter Pointer, LSB
7
Allocation Length, MSB
8
Allocation Length, LSB
9
Control
Field Descriptions
Field
Bytes
Bits
Description
Operation
Code
0
The Operation Code for Log Sense is 4Dh.
Ignored
Logical
Unit
1
5-7
The LUN field is residual from the SCSI-1 days and is ignored.
Page
Control
(PC)
2
6-7
00b = Requests Threshold values (always returns maximum possible
values).
01b = Requests Accumulated values
10b = Requests Default threshold values (always returns maximum
possible values).
11b = Requests Default accumulated values (always returns 0s).
Page
Code
2
0-5
00h = Requests Supported Log Pages Log
02h = Requests Write Error Counters Log
03h = Requests Read Error Counters Log
0Ch = Requests Sequential Access Device Log
2Eh = Requests Tape Alert Log
30h = Requests Tape Usage Log
31h = Requests Tape Capacity Log
32h = Requests Data Compression Log
Parameter
Pointer
5-6
7-0
Specifies the beginning parameter code to be returned to the initia-
tor. All remaining parameter codes are returned in ascending order.
This field is ignored for page code 00h.
