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Scope: Core (OPC-10000-*) All specs

16 result(s) for RedundantServerSet

OPC-10000-4 – OPC Unified Architecture - Part 4: Services

3.1.11 RedundantServerSet

RedundantServerSet two or more Servers that are redundant with each other Note 1 to entry: A RedundantServerSet is a group of Servers that are configured to provide Redundancy . These Servers
OPC-10000-4 – OPC Unified Architecture - Part 4: Services

5.5.2.1 Description

Server . Non-transparent redundant Servers shall provide a record for each Server in the RedundantServerSet . Every Server shall have a globally unique identifier called the ServerUri . This identifier should
OPC-10000-4 – OPC Unified Architecture - Part 4: Services

6.6.2.1 General

receive data are performed by the Client . The Client shall be aware of the RedundantServerSet and shall perform the required actions to benefit from the Server Redundancy . The ServerRedundancy Object
OPC-10000-4 – OPC Unified Architecture - Part 4: Services

6.6.2.2 RedundantServerSet Requirements

RedundantServerSet Requirements OPC UA Servers that are part of a RedundantServerSet have certain AddressSpace requirements. These requirements allow a Client to consistently access information from Servers in a RedundantServerSet ... make intelligent choices related to the health and availability of Servers in the RedundantServerSet . Servers in the RedundantServerSet shall have an identical AddressSpace including: identical NodeIds identical browse paths
OPC-10000-4 – OPC Unified Architecture - Part 4: Services

6.6.2.3.1 Client behaviour

Client behaviour To a Client the transparent RedundantServerSet appears as if it is just a single Server and the Client has no Failover actions to perform. All Servers ... RedundantServerSet have an identical ServerUri and an identical EndpointUrl . Figure 26 shows a typical transparent Redundancy setup. Figure 26 - Transparent Redundancy setup example For transparent Redundancy , OPC UA provides data
OPC-10000-4 – OPC Unified Architecture - Part 4: Services

6.6.2.3.2 Server requirements

previously used Server . Figure 26 provides an abstract view of a transparent RedundantServerSet . The two or more Servers in the RedundantServerSet share a virtual network address and therefore all Servers
OPC-10000-4 – OPC Unified Architecture - Part 4: Services

6.6.2.4.1 Overview

data structures to allow the Client to identify what Servers are available in the RedundantServerSet and also Server information which tells the Client what modes of Failover the Server supports ... NonTransparentRedundancyType ObjectType defined in OPC 10000-5 . The Servers in the non-transparent RedundantServerSet shall use the ServerCapability NTRS defined in OPC 10000-12 for discovery including the registration with
OPC-10000-4 – OPC Unified Architecture - Part 4: Services

6.6.2.4.2 ServiceLevel

ServiceLevel within each sub-range is Server specific. However, all Servers in a RedundantServerSet shall use the same algorithm to determine the ServiceLevel. All Servers, regardless of RedundantServerSet membership, shall
OPC-10000-4 – OPC Unified Architecture - Part 4: Services

6.6.2.4.3 Load balancing

systems where multiple Hot Servers (see 6.6.2.4.5.4 ) are available, the Servers in the RedundantServerSet can share the load generated by Clients by setting the ServiceLevel in the Healthy sub-range ... with the highest ServiceLevel . Clients shall not Failover to a different Server in the RedundantServerSet of Servers as long as the Server is in the Healthy sub-range. This
OPC-10000-4 – OPC Unified Architecture - Part 4: Services

6.6.2.4.4 Server Failover modes

serious problem then its ServiceLevel drops. On recovery, the Server returns to the RedundantServerSet with an appropriate ServiceLevel to indicate that it is available. HotAndMirrored HotAndMirrored Failover mode is where ... Servers that are mirroring their internal states to all Servers in the RedundantServerSet and more than one Server can be active and fully operational. Mirroring state minimally includes Sessions , Subscriptions
OPC-10000-4 – OPC Unified Architecture - Part 4: Services

6.6.2.4.5.1 General

General Each Server maintains a list of ServerUris for all redundant Servers in the RedundantServerSet . The list is provided together with the Failover mode in the ServerRedundancy Object defined ... each Server in the list shall provide the ApplicationDescription for all Servers in the RedundantServerSet through the FindServers Service . This information is needed by the Client to translate the ServerUri
OPC-10000-4 – OPC Unified Architecture - Part 4: Services

6.6.2.4.5.2 Cold

information that is required related to the list of available Servers in the RedundantServerSet . Figure 29 illustrates the action a Client would take if it is talking to a Server
OPC-10000-4 – OPC Unified Architecture - Part 4: Services

6.6.2.4.5.3 Warm

mode is where the Client should connect to one or more Servers in the RedundantServerSet primarily to monitor the ServiceLevel . A Client can connect and create Subscriptions and MonitoredItems ... However, the active Server will return actual data, whereas the other Servers in the RedundantServerSet will return an appropriate error for the MonitoredItems in the Publish response such
OPC-10000-4 – OPC Unified Architecture - Part 4: Services

6.6.2.4.5.4 Hot

mode is where the Client should connect to two or more Servers in the RedundantServerSet and to subscribe to the ServiceLevel variable defined in OPC 10000-5 to find
OPC-10000-4 – OPC Unified Architecture - Part 4: Services

6.6.2.4.5.5 HotAndMirrored

HotAndMirrored Failover mode is where a Client only connects to one Server in the RedundantServerSet because the Server will share this session/state information with the other Servers . In order
OPC-10000-4 – OPC Unified Architecture - Part 4: Services

6.6.5 Manually Forcing Failover

redundant systems, it is common to require that a particular Server in the RedundantServerSet be taken out of the RedundantServerSet for a period of time. Some items that could cause ... patches installation of new software Reconfiguration of the AddressSpace The removal from the RedundantServerSet can be done through a complete shutdown or by setting the ServiceLevel of the Server