Barracuda 18LP Family: ST39175LW/LC ST318275LW ... - Seagate
Barracuda 18LP Family: ST39175LW/LC ST318275LW ... - Seagate
Barracuda 18LP Family: ST39175LW/LC ST318275LW ... - Seagate
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<strong>Barracuda</strong> <strong>18LP</strong> Product Manual, Rev. E 47<br />
Table 8:<br />
Vital product data pages (Continued)<br />
Byte Page Supported<br />
Jumper settings page C2h<br />
0 Peripheral qualifier/peripheral device type Y<br />
1 Page code number C2<br />
2 Reserved 00<br />
3 Page length 02<br />
4 Motor start, parity enable, SCSI ID, delayed motor start, motor Y<br />
start, write protect, parity enable<br />
5 Terminator enable N<br />
9.3.2 Mode Sense data<br />
The Mode Sense command provides a means for the drive to report its operating parameters to the initiator.<br />
The drive maintains four sets of Mode parameters, Default values, Saved values, Current values and Changeable<br />
values.<br />
Default values are hard coded in the drive firmware that is stored in flash EPROM nonvolatile memory on the<br />
drive PCBA. Default values can be changed only by downloading a complete set of new firmware into the flash<br />
EPROM. An initiator can request and receive from the drive a list of Default values and use those in a Mode<br />
Select command to set up new Current and Saved values, where the values are changeable.<br />
Saved values are stored on the disk media using a Mode Select command. Only parameter values that are<br />
allowed to be changed can be changed by this method. See “Changeable values” defined below. Parameters in<br />
the Saved values list that are not changeable by the Mode Select command get their values from the Default<br />
values storage.<br />
Current values are volatile values currently being used by the drive to control its operation. A Mode Select command<br />
can be used to change these values (only those that are changeable). Originally, they are installed from<br />
Saved or Default values after a power on reset, hard reset, or Bus Device Reset message.<br />
Changeable values form a bit mask, stored in nonvolatile memory, that dictates which of the Current values<br />
and Saved values can be changed by a Mode Select command. A “one” allows a change to a corresponding<br />
bit; a “zero” allows no change. For example, in Tables 9a and 9b refer to Mode page 01, in the row entitled<br />
“CHG”. These are hex numbers representing the changeable values for Mode page 01. Note that bytes 04, 05,<br />
06, and 07 are not changeable, because those fields are all zeros. If some changeable code had a hex value<br />
EF, that equates to the binary pattern 1110 1111. If there is a zero in any bit position in the field, it means that<br />
bit is not changeable. Bits 7, 6, 5, 3, 2, 1, and 0 are changeable, because those bits are all ones. Bit 4 is not<br />
changeable.<br />
Though the drive always reports non-zero values in bytes 00 and 01, those particular bytes are never changeable.<br />
The Changeable values list can only be changed by downloading new firmware into the flash EPROM.<br />
On standard OEM drives the Saved values are taken from the Default values list and stored into the Saved values<br />
storage location on the media prior to shipping.<br />
When a drive is powered up, it takes Saved values from the media and stores them to the Current values storage<br />
in volatile memory. It is not possible to change the Current values (or the saved values) with a Mode Select<br />
command before the drive is up to speed and is “ready.” An attempt to do so results in a “Check Condition” status<br />
being returned.<br />
Note.<br />
Because there may be several different versions of drive control firmware in the total population of<br />
drives in the field, the Mode Sense values given in the following tables may not exactly match those of<br />
some drives.