1.1.1

Table Of Contents
Chapter 39
Configuring Discovery Mechanisms
Whether you deploy embedded SQLFire peers or standalone SQLFire servers, members of the same cluster must use
a common discovery method to locate each other. UDP multicast and TCP locators are the two mechanisms supported
for SQLFire member discovery.
Using Locators
A SQLFire locator is a process that tells new, connecting peers and thin clients how to connect to peers that are
already running. Locators also load balance thin client connections to available SQLFire members in a client-server
deployment.
In general, run a locator as its own process (standalone), rather than running a locator process alongside the full
SQLFire engine (on a peer client or a data store). Running standalone locators provides the highest reliability
and availability for the locator service as a whole. Standalone locators are also required for systems that enable
network partitioning management.
Start and Stop Locators
You start and stop locators with the sqlf utility and the locator script. The command line options determine
the address and port at which SQLFire peers communicate with the locator, as well as the address and port that
thin clients use to connect to the SQLFire cluster using the locator.
Start Locators
Always start locator members rst when you start a SQLFire cluster. This ensures that the locators can manage
server discovery from the beginning, as individual SQLFire servers join and leave the cluster.
If your cluster uses multiple locators, specify the complete list of locator addresses and ports when you start
each locator.
For example, the following command starts an initial locator for both peer and client access:
sqlf locator start -peer-discovery-address=locator1host
-peer-discovery-port=10101 \
-locators=locator1host[
10101],locator2host[
20202] \
-client-bind-address=locator1host -client-port=1527 -dir=locator1
The -peer-discovery-address and -peer-discovery-port options dene a unique connection
that all members of this SQLFire distributed system use for communicating with the locator (see Start and Stop
Locators on page 223). The -client-bind-address and -client-port options dene a connection
that client applications can use to connect to the cluster using this locator (see Connect to a Distributed System
Using Locators on page 225).
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