SCSI Commands: 21BLOG SENSE Page 49Field Bytes Bits DescriptionPageCode2 0-5 00h = Requests Supported Log Pages Log02h = Requests Write Error Counters Log03h = Requests Read Error Counters Log0Ch = Requests Sequential Access Device Log0Dh = Requests Temperature Log12h = Requests Tape Alert Response Log14h = Requests Device Statistics Log16h = Requests Tape Diagnostic Log18h = Requests Protocol Specific Port Log (SAS only)2Eh = Requests TapeAlert Log30h = Requests Tape Usage Log31h = Requests Tape Capacity Log32h = Requests Data Compression Log33h = Requests Error Events Log3Eh = Requests Tape Device Statistics LogParameterPointer5-6 7-0 Specifies the beginning parameter code to be returned to the initiator.All remaining parameter codes are returned in ascending order.This field is ignored for page code 00h.AllocationLength7-8 7-0 The Allocation Length field specifies the maximum amount ofmemory space (in bytes), which the initiator has reserved for LOGSENSE data.The drive returns the number of bytes contained in the requestedpage, or the requested Allocation Length, whichever is less. If theAllocation Length is less than the actual page length, the transfer istruncated.Reserved All reserved bits must be 0.Control 9 See SCSI Command Control Byte Format on page 25.The Page Control (PC) field specifies the type of counters that the initiator isrequesting. The value 01b is the most common page control setting. This requeststhe accumulated counts for the page to be returned. These counts reflect the currentcount of events since the last power-on cycle, SCSI bus Reset, Bus Device Reset,Target or Logical Unit Reset, Reset LIP, cartridge loading, or the last LOG SELECTcommand that cleared the parameter values.Accumulated values are incremented by the drive as an event occurs. For pages02h, 03h, and 32h, these values can be cleared with all the above methods. Forpage 0Ch these values can be cleared with all the above methods except with LOGSELECT. Because the drive maintains the accumulated values in volatile memory,the values may be lost if a power cycle occurs.The PC field is ignored for pages 00h, 0Ch, 0Dh, 12h, 14h, 16h, 18h, 2Eh, 30h, 31h,33h, and 3Eh and the accumulated values are always returned except page 00h,which has no accumulated values.3.9.2 Log Sense Parameter Pointer FieldThe Parameter Pointer field specifies the starting page parameter that is to betransferred. For example, if the page uses parameter codes 2 through 6 and theparameter pointer field is set to 3, then the drive returns parameters 3 through 6.Likewise, if the parameter pointer is set to 1, parameters 2 through 6 are returned.
