Starfire Architecture

Each DSD is centrally managed by the SSP. The SSP is an independent workstation loaded with the Solaris operating environment and additional SUNWsspxxx software packages, which manages the Starfire hardware and DSD resource allocation (see FIGURE 8-5). The SSP manipulates system board hardware registers through an Ethernet link attached to the control board to reflect DSD boundaries. The control board converts TCP/IP traffic from the SSP to the JTAG protocol.

The Gigaplane-XB interconnect is at the heart of the Starfire's high performance, availability, and scalability. It uses four interleaved address buses, a 16x16 inter-board data crossbar, and point-to-point routing for all of the interconnect data, arbitration, and address busses. The implementation of point-to-point routing provides the electrical isolation that enforces hardware and software independence between DSDs by filtering all address requests.

There is always at least one DSD in the machine, each containing a minimum of one system board (4 CPUs) and a maximum of 16 system boards (64 CPUs on a fully configured machine).

A primary DSD for the Starfire system is created at the factory using a DSD key, which is a special string of alphanumeric characters required by the SSP to create the required DSD data structures. Each DSD has a unique hostid, a machine identity used by software licensing schemes, which is extracted from the DSD key.

Each DSD is allocated its own directory structure on the SSP, which contains an OBP image as well as hardware logs that are being extracted on a continuous basis. Each DSD forwards system logs to the SSP through the syslog.conf(4) file, which builds a centralized error message repository in the SSP's /var/adm/messages log file.

FIGURE 8-6 shows the Hostview GUI, the system administration application on the SSP, which provides a visual representation of DSDs and the Starfire platform. All system boards and active/standby control boards plug into the centerplane (eight system boards plus a control board in the front and eight system boards plus a spare control board in the back). The active centerplane has four address buses and two paths to each half of the data crossbar. When viewed on the screen, each system board icon has a color border representing the DSD to which it belongs.