CTDB has the following limitations on GNU Hurd:

- The pid of a peer is not get from the socket [1]. As a consequence, the peer
  process is not killed when releasing IP [2].

- network interfaces are always considered present [3]

- Some other functions are not yet supported [4]

[1]: ctdb_get_peer_pid() in common/system_gnu.c
[2]: release_kill_clients() in server/ctdb_takeover.c
[3]: ctdb_sys_check_iface_exists() in common/system_gnu.c
[4]: See FIXME in common/system_gnu.c (ctdb_sys_send_arp(),
     ctdb_get_process_name(), ctdb_get_lock_info(), ctdb_get_blocker_pid())