Avaya Aura System Platform Installing And Configuring page 97

Note:
During the initial synchronization, the online changes are also propagated. It is essential to provide
enough network throughput for the successful completion of the online changes. Thus the System
Platform sets the DRBD initial synchronization rate to 30MB/s. You can modify this value from the
Failover page in case system is not overloaded.
DRBD online propagation of data changes
System Platform High Availability Failover uses the Distributed Replicated Block Device component to
propagate online changes that are made on the active node. It uses its protocol "C" which ensures that
writing to the local hard disk is only confirmed when the same write is acknowledged on the remote node.
This ensures that the machines are kept in consistent state to enable the standby node to takeover when
required. The following image depicts the data propagation from active node to the standby node:
In the event of failover or switchover when the node roles are changed (that is, the active node becomes
the standby node and vice versa), the propagation direction swaps to ensure that the changes on the
active node are propagated to the current standby node. The following image depicts data propagation
after a failover/switchover:
Installing and Configuring Avaya Aura
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System Platform April 2010 97