RA7000 and ESA10000 Storage Subsystems
1–10
EK–SMCPP–UG. A01
The maximum bus length, including external cables (distance from the I/O
module terminator to the last terminator on the bus) is a function of the bus speed
and the number of devices. If the external bus is configured point to point (from
SE I/O module-to-SE I/O module with no devices installed in between), the
cables may be extended to 20 meters due to the isolation and re-timing circuitry
of the SE I/O module.
1.3
Error Detection and Reporting
The subsystem error detection and reporting function has two major elements –
the fault bus and the EMU (environmental monitor unit). For a detailed
discussion of error detection, fault reporting, and correction, refer to Chapter 4,
Error Analysis and Fault Isolation.
1.3.1 Fault Bus
The subsystem fault bus monitors subsystem operation and reports fault
conditions to the HSZ70 RAID array controller and the EMU. The controller and
EMU then report the error condition to the user. The fault bus monitors the
following conditions:
•
Blower failure (SHELF_OK)
•
Power supply failure (SHELF_OK)
•
Storage device removal (SWAP_L)
•
Storage device installation (SWAP_L)
•
SBB failure (FAULT_CLK, FAULT_DATA)
The fault bus consists of three subsystem backplane signals routed to the
controller port connectors as follows:
•
Shelf Status Signal – The SHELF_OK status signal indicates the state of
subsystem power (ac and dc) and blower operation
•
SBB Swap Signal – The SWAP_L signal is asserted whenever an SBB is
removed from or inserted in the subsystem
•
SBB Fault Signals – The SBB amber LED displays either the storage
address or indicates a device fault. This device fault LED is controlled by
the fault clock (FAULT_CLK) and the fault data (FAULT_DATA) control
signals.
