# Starting Fault Tolerant Server Pairs

In Central Administration, fault tolerant pairs share a single JSON configuration file. Primary and secondary server roles are determined when the servers are started.

Start the primary EMS server as usual. Start the secondary server using the -secondary flag. For example, where the JSON configuration file is `tibemsd.json`:

- To start the primary server:

  `tibemsd -config tibemsd.json`

- To start the secondary server:

  `tibemsd -config tibemsd.json -secondary`

For more information, see Fault Tolerance in Central Administration.

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