Intel ZT 4901 manual High Availability Hardware Approach

Introduction

Split Mode—Split Mode is a term that refers to a system operating with multiple system master Host boards that each own a single bus segment. Split Mode may refer to either Active/Active or cluster modes. In an Active/Active either of two Hosts can inherit the other Host’s bus segment. In cluster mode each Host’s bus segment is locked to that Host and ownership cannot be transferred to the other Host.

Standby Host (also known as the standby system master)—System board in a High Availability system that is currently operating in Drone Mode and therefore not the Active Host. The Standby Host has no visibility of the devices on the other side of the PCI-to-PCI bridge.

Switchover—Changing ownership of a domain from one Host to another.

System Host functions—Central functions provided to a CompactPCI bus segment including hot swap event response, bus enumeration, and interrupt service. The system slot board provides these functions.

System slot—Slot occupied by a System Master that performs arbitration for secondary bus masters, responds to interrupts from peripheral boards, and drives a clock signal to each backplane slot.

Takeover—A type of switchover that is initiated by the Standby Host in a High Availability system. A takeover may be hostile or friendly.

Warm Switchover—A warm switchover refers to the state of the domain that is being inherited by the Host taking ownership. On a warm switchover domain ownership is transitioned and, before any bus actions or operations are allowed to occur, the bus segment is toggled through reset. This in effect resets all the devices that reside in the reset domain.

2.2High Availability Hardware Approach

In an RH system the Redundant System Slot (RSS) subsystem is spread across several building blocks. These include:

•Processor boards (such as the Intel® NetStructure™ ZT 5524 System Master Processor Board)

•Bridge mezzanine (such as the Intel® NetStructure™ ZT 4901 Mezzanine Expansion Card)

•Backplane (such as the Intel® NetStructure™ ZT 4103 Redundant Host Backplane)

Other building blocks and subsystems may be required to support the RSS subsystem. These include:

•System management

•Storage

•Power distribution

•Cooling

•Media

•Packet switching

14 High Availability Software for the Intel® NetStructureTM ZT 4901 Technical Product Specification