Blackberry blackberry enterprise server for microsoft exchange manual

Feature and Technical Overview BlackBerry Enterprise Server high availability

High availability in a distributed environment

If you install multiple BlackBerry Enterprise Server components on different computers to create a distributed environment, you can configure the components for high availability. High availability for a distributed component requires that you install two or more instances of the component in your organization's environment. When an instance stops responding, the other instances can take over.

When you install multiple BlackBerry Enterprise Server components in a distributed environment, each BlackBerry Enterprise Server component implements high availablility differently.

Component	High availability type	Description
BlackBerry Administration	load balancing using DNS	When you install two or more BlackBerry Administration
Service	round robin, or a hardware	Service instances, you can create a BlackBerry
	load balancer	Administration Service pool. You can access the BlackBerry
		Administration Service instances using a single web
		address. The load is distributed across the instances. If a
		BlackBerry Administration Service instance stops
		responding, the pool routes requests to the available
		instances.
BlackBerry Attachment	load-balancing with primary	When you install two or more BlackBerry Attachment
Service	and secondary groups	Service instances, you can create a BlackBerry Attachment
		Service pool for each BlackBerry Enterprise Server
		instance. You can configure a pool with a primary group of
		instances and, optionally, a secondary group of instances.
		The BlackBerry Enterprise Server sends all requests to the
		primary group. If the primary group cannot convert a
		specific file format, the BlackBerry Enterprise Server
		forwards conversion requests for the specific file format to
		the secondary group.
BlackBerry Collaboration	failover with an active	When you install two or more BlackBerry Collaboration
Service	connection to one instance	Service instances, you can create a BlackBerry
	and standby connections to	Collaboration Service pool for each BlackBerry Enterprise
	other instances	Server instance. Each BlackBerry Enterprise Server assigns
		one of the connections to the BlackBerry Collaboration
		Service instances as the active connection, and the other
		connections as standby connections. If the BlackBerry
		Collaboration Service that the active connection is assigned
		to stops responding, the BlackBerry Enterprise Server

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