1.0

Table Of Contents
Each gateway sender denes:
A unique identier
The remote distributed system ID where the sender forwards DML operations.
The server group(s) on which to deploy gateway sender instances.
Optional variables to control the connection, persistence, and startup behavior for the sender and its queue.
Notice that each gateway sender only species the remote distributed system ID to use for replicating DML
operations. The actual connection information (the host and port number of a gateway receiver in the remote
distribute system) are obtained dynamically from the cluster locators. Locators automatically update this
information as gateway receivers in remote sites change or go ofine.
How Gateway Sender Startup Policy Affects Startup Behavior
This applies to systems where a gateway sender is installed to multiple data store members. When a gateway
sender is deployed to multiple data stores, only one primary sender is active at any given time. All other gateway
sender instances are secondaries that act as backups to the primary.
SQLFire designates the rst gateway sender to start up as the primary sender, and all other senders become
secondaries. As gateway senders are started and shut-down in the distributed system, SQLFire ensures that the
oldest running gateway sender operates as the primary.
About High Availability for WAN Deployments
You can deploy a gateway sender to multiple data stores to provide high availability.
At any given time, only one member has an active gateway sender process, called the primary sender, for
propagating DML to a remote WAN site. All other gateway senders of the same name are treated as secondary
senders. Secondary senders remain in standby mode for redundancy, to guarantee replication to the remote WAN
site if the member with the primary sender fails.
A SQLFire cluster needs only a single gateway receiver to receive DML events from remote distributed systems.
However, as with gateway senders, you can deploy multiple instances of the gateway receiver to different SQLFire
members for high availability.
Gateway senders can also be congured to use an available disk store to persist queued DML operations that
need to be replicated to a remote cluster. Using a disk store ensures that queued DML operations are not lost,
even if you shut down the SQLFire member that hosts the primary sender.
221
Configuring Multi-site (WAN) Deployments