Areca ARC-1222 - Page 21

HARDWARE INSTALLATION
21
Step 6. Install the LED Cable (option)
The preferred I/O connector for server backplanes is the Min SAS 4i
internal 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 efcient LED management and for sensing drive Locate status.
See SFF 8485 for the specication 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 SAS RAID controller, could control the LEDs. Activ-
ity: 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.
The following signals dene the SGPIO assignments for the Min
SAS 4i internal connector (SFF-8087) in the SAS RAID controller.
PIN Description PIN Description
SideBand0 SClock (Clock signal) SideBand1 SLoad (Last clock of a bit
stream)
SideBand2 Ground SideBand3 Ground
SideBand4 SDataOut (Serial data
output bit stream)
SideBand5 SDataIn (Serial data input bit
stream)
SideBand6 Reserved SideBand7 Reserved
Step 7. Adding a Battery Backup Module (optional)
Please refer to Appendix B for installing the BBM in your SAS RAID
controller.