Keepalived is used for monitoring real servers within a Linux Virtual Server (LVS) cluster. keepalived can be configured to remove real servers from the cluster pool if it stops responding, as well as send a notification email to make the admin aware of the service failure.

In addition, keepalived implements an independent Virtual Router Redundancy Protocol (VRRPv2; see rfc2338 for additional info) framework for director failover.

You need a kernel >= 2.4.28 or >= 2.6.11 for keepalived. See README.Debian for more information.