The i386™ clients co-located with pointyhat netboot from it (connected nodes); all other clients (disconnected nodes) are either self-hosted or netboot from some other pxe host. In all cases they set themselves up at boot-time to prepare to build packages.
The cluster master rsyncs the interesting data (ports and src trees, bindist tarballs, scripts, etc.) to disconnected nodes during the node-setup phase. Then, the disconnected portbuild directory is nullfs-mounted for chroot builds.
The ports-${arch} user can ssh(1) to the client nodes to monitor them. Use sudo and check the portbuild.hostname.conf for the user and access details.
The scripts/allgohans script can be used to run a command on all of the ${arch} clients.
The scripts/checkmachines script is used to monitor the load on all the nodes of the build cluster, and schedule which nodes build which ports. This script is not very robust, and has a tendency to die. It is best to start up this script on the build master (e.g. pointyhat) after boot time using a while(1) loop.