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OCPRF100 MP Server System Technical Product Specification
Revision 1.0
93
² Spin-down of a drive when failure is detected and reported (using enclosure services
messages) via the SCSI bus. An application or RAID controller detects a drive-related
problem that indicates a data risk. In response, it takes the drive out of service and sends
a spin down SCSI command to the drive. This decreases the likelihood that the drive is
damaged during removal from the hot-swap drive bay. When a new drive is inserted, the
power control waits a small amount of time for the drive to be fully seated, and then
appiles power to the drive to prepare for operation.
² If system power is on, the backplane immediately powers off a drive slot when it
detects a drive has been removed. This prevents possible damage to the drive when it is
partially removed and reinserted while full power is available. It also prevents disruption
of the entire SCSI array due to possible sags in supply voltage and resultant current
spikes.
8.2.5 FET Short Protection
The FET short protection circuit is useful to protect both 12 volt and 5 volt power control FETs
located on the backplane.
8.2.6 Microcontroller
The microcontroller provides all the intelligence for the LVDS SCSI backplane. It is an 80C652
microcontroller, with a built-in I
2
C interface. The 80C652 microcontroller uses Flash for program
code storage, and static RAM for program variables and buffers.
8.2.7 LED Arrangement
The three LEDs per drive are arranged as follows (viewed from the drive bay):
Figure 8-3: LED Arrangement
8.2.7.1 Power LEDs
Power LEDs are green and they indicate the drive is receiving power. Power LED control is
driven by the FET switched +5 volts applied to the drive.
8.2.7.2 Drive Activity LEDs
The activity LEDs are green and are driven by the drive, pin 77, and interfaces directly to the
LED.
Green
Power
LED
Green
Activity
LED
Yellow
Fault
LED