User`s guide

26 NovaScale 4020 User’s Guide
SCSI Backplane Board
The SCSI backplane board connection layout is shown in Figure 20. The SCSI backplane
board communicates with the main board via a 68-pin SCSI cable and to the Front Panel board
via a 20-pin ribbon cable. It contains two industry standard 80-pin Single Connector
Attachment (SCA)-2 connectors for hot-swap hard drives. Ultra320 or lower SCSI technology
SCA type hard drives can be installed in this carrier. The backplane board accepts hard drives
up to 15,000-RPM.
The features supported by the SCSI backplane board include the following:
• Monitoring the SCSI bus for enclosure services messages and acting on them appropriately.
Examples of such messages include: activate a drive fault indicator, power down a drive
that has failed, and report SCSI backplane temperature.
• SAF-TE intelligent agent, which acts as proxy for “dumb” I
2
C devices during intra-chassis
communications. “Dumb” I
2
C devices are those that have no bus mastering capability.
The SCSI backplane provides three main functions for the system:
• It passes the SCSI signals between the main board and the SCSI drives
• It provides hooks for enclosure management
• It provides an I
2
C server management interface
The SCSI backplane functional blocks include the following:
• Ultra320 LVD SCSI bus passes SCSI signals between the SCSI drives and the main board
 A standard 68-pin SCSI connector provides the SCSI connection from the main board
to the SCSI backplane
 Two 80-pin (SCA-2 blind-mate) connectors are located on the SCSI backplane board to
mate with hot-swap LVD SCSI drives in the drive bay
• Fault Tolerant Enclosure Management
 SAF-TE
 SCSI power control
 LED control logic
• Server management
 I
2
C interface
 I
2
C Serial CMOS EEPROM (FRU)
 Temperature sensor