gistfile1.xml

<!-- LON site, the cache below backups to NYC. It doesn't have any clue which site from NYC acts as a backup. -->
<namedCache name="local-users">
   <sites>
     <backups>
       <backup site="NYC" backupFailurePolicy="WARN" strategy="SYNC"/>
     </backups>
  </sites>
</namedCache>

<!-- -------------------------------------------------------------------------------------------------------- -->

<!-- NYC site. Whenever a remote write from users@LON is received by this site, the data is backed up into 
this cache. If the backupFor is missing from all the defined caches, then the name of the backup defaults 
to remote cache name, i.e. users) -->
<namedCache name="users">
   <sites>
     <backupFor remoteCache="local-users" remoteSite="LON"/>
  </sites>
</namedCache>