Commands 63
Commands
Log Page Format
All log pages except Page 0 consist of a page code header followed by a
number of parameters. The page header has the following format:
The page code is a byte value that uniquely identifies which Log Page is being
returned. The Page Length indicates the number of additional bytes in the
parameters.
For the
Log Select command only, the four bytes shown above are sent for each
log page to be cleared. The Page Length field should be set to zero.
For the
Log Sense command one or more parameters is sent. See the actual
page descriptions above for more information. Note that all the parameters for
a particular page must be sent. Each parameter has the following format:
11b Default Cumulative Values—any parameters in the log that are counters contain the initial
values of those counters (set at power-on, reset, bus device reset and, in the case of media
logs, load).
The PC field has no effect on the data returned when the selected log contains event or trace codes
rather than counts.
Page Code The Page Code field identifies which log page is being requested by the host. See
page 64 for
the list of valid page codes.
Allocation
Length
The Allocation Length field specifies the maximum number of bytes of data that should be returned
to the host. The drive will return the entire log or Allocation Length bytes, whichever is the lesser.
7 6 5 4 3 2 1 0
0
Page Code
1
Reserved (0)
2
(MSB)
Page Length
3
(LSB)
7 6 5 4 3 2 1 0
0
(MSB)
Parameter Code
1
(LSB)
2
DU (0) DS (1) TSD (0) ETC (0) TMC(0) LBIN LP
