Log Select; Command Descriptor Block - Seagate Viper 200 Scsi Interface Manual

Page 38

LOG SELECT

Command Descriptor Block

Field Descriptions
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.
The Log Select command is used to reset the log counters to their default values. A
SCSI Bus Reset, Bus Device Reset, or cartridge loading is also used to reset these
counters (of pages 02h, 03h, 0Ch, and 32h). Multiple pages are reset by a single Log
Select command. Log Select affects pages 02h, 03h, 2Eh, and 32h only. See Log
Sense for information about log pages and their format.
Bits
Byte 7 6
0
1 Ignored LUN
2
PC
3
4
5
6
7
8
9
Field Bytes Bits
Operation 0
Code
Ignored 1 5-7
Logical
Unit
Parameter 1 1
Code Re-
set (PCR)
Page 2 6-7
Control
(PC)
Parameter 7-8
List
Length
Reserved
5 4 3
Operation Code (4Ch)
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Parameter List Length, MSB
Parameter List Length, LSB
Control
Description
The Operation Code for Log Select is 4Ch
The LUN field is residual from the SCSI-1 days and is ignored.
0 = Reset values as specified by PC. Do not clear the DU (Disable
Update, see Log Parameter) bits of the parameters of log pages
02h, 03h, 2Eh, and 32h. With page 2Eh log parameters are set to
0 only when PC = 11b.
1 = Reset log parameters on pages 02h, 03h, 2Eh, and 32h. All ac-
cumulated values are set to 0; all threshold values are set to
maximums except page 2Eh. DU bits of the parameters of these
log pages are also cleared.
00b = Check Condition if Parameter List Length > 0.
01b = Check Condition if Parameter List Length > 0.
10b = All thresholds are set to maximums. Check Condition if Pa-
rameter List Length > 0.
11b = All accumulated values are set to 0. Check Condition if Pa-
rameter List Length > 0.
This field is ignored if PCR is not 0.
Always 0. Specifies the length (in bytes) of the parameter list to be
transferred during the Data Out phase. A 0 length indicates that no
parameter data is to be transferred.
All reserved bits must be 0.
LTO SCSI Interface Manual
2 1 0
PCR Reserved