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Cheetah NS SAS Product Manual, Rev. B
On standard OEM drives, the saved values are taken from the default values list and stored into the saved
values storage location on the media prior to shipping.
3.
Current values
Current values are volatile values being used by the drive to control its operation. A Mode Select command
can be used to change the values identified as changeable values. Originally, current values are installed
from saved or default values after a power on reset, hard reset, or Bus Device Reset message.
4.
Changeable values
Changeable values form a bit mask, stored in nonvolatile memory, that dictates which of the current values
and saved values can be changed by a Mode Select command. A one (1) indicates the value can be
changed. A zero (0) indicates the value is not changeable. For example, in Table 9.3.2.1, refer to Mode
page 81, in the row entitled “CHG.” These are hex numbers representing the changeable values for Mode
page 81. Note in columns 5 and 6 (bytes 04 and 05), there is 00h which indicates that in bytes 04 and 05
none of the bits are changeable. Note also that bytes 06, 07, 09, 10, and 11 are not changeable, because
those fields are all zeros. In byte 02, hex value FF equates to the binary pattern 11111111. If there is a zero
in any bit position in the field, it means that bit is not changeable. Since all of the bits in byte 02 are ones,
all of these bits are changeable.
The changeable values list can only be changed by downloading new firmware into the flash E-PROM.
Note.
Because there are often several different versions of drive control firmware in the total population of
drives in the field, the Mode Sense values given in the following tables may not exactly match those
of some drives.
The following tables list the values of the data bytes returned by the drive in response to the Mode Sense com-
mand pages for SCSI implementation (see the SAS Interface Manual ).
Definitions:
DEF = Default value. Standard OEM drives are shipped configured this way.
CHG = Changeable bits; indicates if default value is changeable.
Summary of Contents for Cheetah NS SAS ST3400755SS
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