1.2
System Architecture Overview
The Ultrastar Data60 IOM uses a cascaded expander design to allow for connection to all 60 drives. A 48-port
primary expander connects with the six host ports, has a x3 link to the other IOM for IOM-IOM communication
and syncing, and also has a x10 SAS link to each secondary expander. Each secondary expander then
connects with fifty-one (51) drives.
The out-of-band management microprocessor provides an Ethernet connection using a Redfish/RESTful API
to access the various enclosure services. All the SES enclosure information can be obtained through the
out-of-band management port. Major use cases for this feature include obtaining storage subsystem health
information, locating enclosure components using the IDENT LEDs, and updating firmware.
The system FPGAs control and report the states of the system fans, enclosure LEDs,connector LEDs, drive
LEDs, and T10 drive power disable signals on the 60 data storage drives.
Note: To use T10 power disable, the drives installed must also support this
feature.
The I
2
C architecture is designed to support only one single master on any given bus. The primary expander
will be the master on each I
2
C bus. There are eight I
2
C buses used in the Ultrastar Data60 enclosure. The
number of devices on each bus are balanced to allow communication to peripheral devices and not overload
any one bus. The devices connected on the I
2
C buses include the enclosure VPDs, temp sensors, baseboard
FPGAs, and SAS connectors among others.
11
1
Overview
User Guide
1.2
System Architecture Overview
