Rockwell Automation FactoryTalk View Site Edition Users Guide - Manual (Page 363)

14 • S ETTING UP F ACTORY T ALK SYSTEM AVAILABILITY
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In the Components tab, you can also start and stop components manually, on both the
primary and the secondary HMI server. For details about options in the Components tab,
click Help.
Ensuring that macros finish running
If the Active HMI server in a redundant pair fails while a command or macro is running,
the command or macro stops running, during failover to the Standby server.
You might have to re-run the command or macro when the failover process finishes, and
the Standby server becomes active.
What happens if both servers become active
If a network disconnection breaks communications between the primary and secondary
HMI server computers, it is possible for both servers to be in an active state, when the
network is restored.
In a partitioned network, for example, where a switch exists between the primary and
secondary host computers, clients on the primary server side of the switch would remain
connected to the Active primary server, when a network break occurs.
Meanwhile, on the secondary server side of the switch, the secondary server would detect
that the primary server has failed, and become active. Clients on that side of the switch
would connect to the newly Active secondary server.
When the network is restored, if redundancy options are set up to continue using the
Active secondary server, then both the primary and the secondary HMI servers would
remain active.
If that happens, the HMI servers would use the following criteria to determine whether the
primary or the secondary server should be active:
 If one HMI server in the redundant pair has more clients connected to it, then the
server with the most clients will become the Active server.
The server with the least clients will become the Standby server, and the clients
connected to this server will reconnect to the new, Active server.
 If the HMI servers have an equal number of clients connected them, the primary
server will become active, and the secondary server will go on standby.
If an On Active macro contains many commands (or other macros), it might not finish running
before the HMI server is finished becoming active. This means that the macro might still be
running, when the server is ready to accept requests from clients.