Operating instructions

8-2
SCSI REFERENCE 1012975
CHAPTER 8—LOG SENSE (4Dh)
8.2 WHAT YOU SEND TO THE AUTOLOADER
PPC (Parameter Pointer Control) – Byte 01, Bit 1
The value for the PPC field must be 0. This directs the autoloader to return the
number of bytes that you specify in the Allocation Length field, beginning
with the parameter code specified in the Parameter Pointer field (bytes 05 and
06). The autoloader returns the bytes in ascending order of parameter codes
from the specified log page. When both the PPC bit and the Parameter Pointer
field are set to 0 and the Allocation Length is sufficient, the autoloader returns
all available log parameters for the specified log page to the initiator.
SP (Saved Parameters) – Byte 01, Bit 0
The value for this field must be 0, indicating that the autoloader will perform
the LOG SENSE command and will not save log parameters.
PC (Page Control) – Byte 02, Bits 6 and 7
This field is always ignored and treated as if it contained the value 01h. This
indicates that the autoloader will always return the cumulative values for any
log parameter requested. The autoloader does not support any threshold
values or default cumulative values.
Page Code – Byte 02, Bits 0 through 5
The Page Code field allows you to identify the page that you want the
autoloader to return. The value for this field must be one of the values
specified in Ta b l e 8 - 1 ; otherwise, the autoloader terminates the command with
Check Condition status and sets the sense key to Illegal Request with the ASC
set to Invalid Field in CDB.
Table 8-1 Valid values for the Page Code field
Page Code Page Name Description
00h Supported Log Pages Returns a list of supported log pages.
2Eh TapeAlert Returns information from the autoloader’s internal TapeAlert
microcode. This microcode constantly monitors the autoloader for
errors and potential difficulties. When a problem is detected, the
autoloader sets a flag on this page to identify the type of problem
detected.
30h System Statistics Returns system statistics and retry counts.
33h Element Statistics Returns element statistics and retry counts.
34h Scan Retry Returns the number of times the autoloader had to retry scanning the
cartridge at the specified element address.
36h Environment Returns environmental statistics
37h Command Failure Returns information on last command failures