HARDWARE INSTALLATION
17
Figure 2-5, Connecting to Backplane
Step 6. Install the LED Cable (Optional)
The preferred I/O connector for server backplanes is the internal
SFF-8087 connector. This connector has eight signal pins to support
four SAS/SATA drives and six pins for the SGPIO (Serial General
Purpose Input/Output) side-band signals. The SGPIO bus is used
for efficient LED management and for sensing drive Locate status.
See SFF 8485 for the specification of the SGPIO bus. For backplane
without SGPIO supporting, Please refer to Section 2.4 LED cables
for fault/activity LED cable installation.
LED Management: The backplane may contain LEDs to indicate
drive status. Light from the LEDs could be transmitted to the out-
side of the server by using light pipes mounted on the SAS drive
tray. A small microcontroller on the backplane, connected via the
SGPIO bus to a 6Gb/s SAS RAID controller, could control the LEDs.
Activity: blinking 5 times/second and Fault: solid illuminated
Drive Locate Circuitry: The location of a drive may be detected by
sensing the voltage level of one of the pre-charge pins before and
after a drive is installed.
