code: private void triggerRSyncSynchronization()
     {
        // Call RSync to retrieve actual index from coordinator
        if (modeHandler.getMode() == IndexerIoMode.READ_ONLY)
        {
           EmbeddedCacheManager cacheManager = cache.getCacheManager();
  
           if (cacheManager.getCoordinator() instanceof JGroupsAddress
              && cacheManager.getTransport() instanceof JGroupsTransport)
           {
              JGroupsTransport transport = (JGroupsTransport)cacheManager.getTransport();
              // Coordinator's address
              org.jgroups.Address jgAddress = ((JGroupsAddress)cacheManager.getCoordinator()).getJGroupsAddress();
              // if jgAddress is UUID address, not the physical one, then retrieve via channel
              if (!(jgAddress instanceof IpAddress))
              {
                 // this is the only way of getting physical address. 
                 Channel channel = transport.getChannel();
                 jgAddress = (org.jgroups.Address)channel.down(new Event(Event.GET_PHYSICAL_ADDRESS, jgAddress));
              }
              if (jgAddress instanceof IpAddress)
              {
                 String address = ((IpAddress)jgAddress).getIpAddress().getHostAddress();
                 RSyncJob rSyncJob =
                    new RSyncJob(String.format(urlFormatString, address), indexPath, rsyncUserName, rsyncPassword);
                 try
                 {
                    // synchronizing access to RSync Job.
                    // No parallel jobs allowed
                    synchronized (this)
                    {
                       rSyncJob.execute();
                    }
                 }
                 catch (IOException e)
                 {
                    LOG.error("Failed to retrieve index using RSYNC", e);
                 }
              }
              else
              {
                 LOG.error("Error triggering RSync synchronization, skipped. Unsupported Address object : "
                    + jgAddress.getClass().getName());
              }
           }
           else
           {
              LOG.error("Error triggering RSync synchronization, skipped. Unsupported Address object : "
                 + cacheManager.getCoordinator().getClass().getName());
           }
        }
     }
docs: Call to system RSync binary implementation,