Honeywell Uniformance R300, User Manual

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4 Overview of Uniformance PHD
4.3
Multiple PHD Server Systems
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Uniformance PHD OPC Server User Guide
4.3 Multiple PHD Server Systems
The Uniformance PHD end user may choose to configure multiple PHD Servers in a system
in order to distribute history collection and storage. There are three possible configuration
options that may be used. You can configure multiple PHD Servers to:
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Operate so a single server effectively hides, or Shadows, one or more additional servers
from view by some client applications. In this configuration, all servers share the
identical configuration data. Shadow servers provide for isolation of the client from
other server environments while also distributing the dynamic load.
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Operate as peers, where clients must access each server directly. Unlike the Shadow
server configuration, peer servers are autonomous, each having its own unique
configuration data.
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Operate as a mixture of both shadow and peer configurations.
The following figure illustrates the complexity you may encounter in a multiple PHD Server
system where multiple DCS systems have also been integrated, and the historical real-time
database is configured for use by applications in both the Level 3 and Level 4 operating
domains.
The configuration illustrated in the following figure is representative of many existing
Uniformance PHD installations. When DCS systems are introduced to such configurations,
the PHD OPC Server provides the consistent interface to each PHD Server; however, the
DCS system and its functions for system management and security introduce additional
complexity which should be considered in the system configuration.