Linux Cluster Project a community project sponsored by Red Hat. Includes a DLM, a clustered file system (GFS) and a High-Availability component.
Keepalived: keepalive facility for LVS. The main goal of the keepalived project is to add a strong and robust keepalive facility to the Linux Virtual Server project. This project is similar to the MON project, but it is in C with multilayer TCP/IP stack checks. Keepalived implements a framework based on three family checks : Layer3, Layer4 & Layer5.
EZHA: open HA clustering package. An "easy to use" cluster HA tool, able to manage up to 16 nodes, using network links or raw devices for heartbeat links, working fine on Linux and SUN Solaris. It has a small GUI.
Linux Replicated High Availability Manager (freshmeat). Linuxha.net is a toolset that attempts to allow two node high availability clusters to be built under Linux using simple inexpensive hardware. Rather than using a single data image (made available via SCSI or Fibre Channel connected storage) Linuxha.net instead replicates the data between the two machines.
Mission Critical Linux's Kimberlite Open Source High-Availability system.
Jerome Etienne's VRRP implementation. Jerome implemented VRRPv2 as specfied by rfc2338.
Fake: Redundant server switch software home page
SGI's Linux FailSafe project. Linux FailSafe is the most complete and functional open source HA software. Unfortunately, it's pretty much dead on Linux
HP's Cluster Infrastructure for Linux. This project is developing a kernel-based infrastructure for Linux clustering by extending the Cluster Membership and Internode Communication Subsystems from HP's NonStop Clusters for SCO Unixware code base.
HP's Single System Image (SSI) Clusters for Linux. The SSI project incorporates HP's NonStop Clusters for SCO Unixware technology and other open source technology to provide a full, highly available SSI environment for Linux.
HAPPI High Availability Peer-to-Peer Implementation. HAPPI is a simple Perl-based high availability clustering technology that uses IP aliasing for IP-failover across a number of machines.
Dominque Chabord's Shaman-X software - providing opensource and free high-availability disaster tolerance, and crisis management software.
Ericsson's Eddie open source High-Availability Server farm project. It is written in Ericsson's own programming language Erlang/OTP.
Mnesia is a distributed Database Management System designed to handle failovers as part of Eddie.
Clusterit: parallel clustering software for *BSD systems.
Andreas Muller's HA-failover project. It seems like a nice implementation, mainly targeted at Solaris. Here is a summary from email he sent me:
Andrew Barnett's pl-cluster software. Andrew wasn't happy with heartbeat, so he wrote his own version. It uses multicast, and can run in listen-only mode. According to Andrew "It is alpha at best, YMMV".
Life (LInux Failover Extension) software for the Linux Virtual Server.
SRRD is the Service Routing Redundancy Daemon. SRRD was designed and developed starting September 2002 by Amir Guindehi <amir@srrd.org> as a master thesis at the Swiss Federal Institute of Technology in Zurich.
Failoverd (discontinued): Failover daemon home page. Failoverd is now VRRP-based.
Ninja: Highly Available, Scaleable Computing Environment.