Feedbackd is an add-on to the Linux Virtual Server project (LVS) to provide dynamic feedback of server health. Feedbackd is open source software, released under the GNU General Public Licence (GPL).

By sending server load information to a LVS-based director, feedbackd can help to stabilise request workload, improving performance and reliability.

Performance effects of feedbackd system are discussed in this paper (PDF, 95kB), which was presented at the Australian Linux Conference (2003).


Feedbackd is based around the Network Element Control Protocol (NECP), a TCP-based protocol designed specifically for communicating server load information. At present, not all functionality of NECP is included, but future versions of feedbackd will become closer to a full implementation.

Feedbackd consists of two separate programs: a master and an agent. The master process is a daemon process run on the director node. It listens for connections from agents, requests server health information and updates the load balancing tables to redistribute the request load.

An agent process is run on each of the server nodes. When started, an agent will contact the master node and send server health information when requested.

Read the feedbackd HOWTO for a more detailed guide to installing and running feedbackd.


The feedbackd master and agent programs are distributed as a single package:


  • The feedbackd HOWTO provides a guide for installing, configuring and running feedbackd on a LVS cluster
  • The paper (presented at Linux.conf.au 2003) discussing performance effects of feedbackd is available here