NonStop NS16000 Series Planning Guide (H06.11+)

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Logical Synchronization Unit (LSU)
The LSU is the heart of both the high-availability duplex NonStop Blade Complex and the
fault-tolerant triplex NonStop Blade Complex. In Integrity NonStop NS16000 series systems, each
LSU is associated with only one logical processor.
The LSU is the gateway to the ServerNet fabrics for the duplex or triplex NonStop Blade Complexes.
It ensures that I/O from logical processors is valid before allowing it into the ServerNet fabric. The
LSU module compares I/O streams between the output of each NonStop Blade Element to ensure
validity of the data. No data leaves the confines of a single NonStop Blade Element without being
compared to and validated with the data from the other NonStop Blade Element (duplex processor)
or the other two NonStop Blade Elements (triplex processor).
The LSU enclosure, which is 4U high and weighs 96 pounds (43.5 kilograms) when fully populated,
has these physical attributes:
• Rackmountable
• Redundant AC power feeds
• Front to rear cooling
• Connections for three NonStop Blade Elements
• Connections for two ServerNet fabrics
• Cable management and connectivity on the rear of the cabinet
Logically the LSU:
• Implements a fault domain that affects only a single logical processor
• Has environmental sense and control (ESC) aspects managed by the logical processor
• Supports single-point system power-on
The LSU module consists of two types of FRUs:
• LSU logic board (accessible from the front of the LSU enclosure)
• LSU optics adapters (accessible from the rear of the LSU enclosure)
• AC power assembly (accessible from the rear of the LSU enclosure)
CAUTION: To maintain proper cooling air flow, blank panels must be installed in all slots
that do not contain logic adapter PICs or logic boards.
This illustration shows an example LSU configuration as viewed from the rear of the enclosure and
equipped with four LSU optics adapter PICs in positions 20 through 23:
110 Modular System Hardware