1. Subsystem for High-Availability Linux heartbeat is a basic heartbeat subsystem for Linux-HA. It will run scripts at initialisation, and when machines go up or down. This version will also perform IP address takeover using gratuitous ARPs. It works correctly for a 2-node configuration, and is extensible to larger configurations. It implements the following kinds of heartbeats: * Bidirectional Serial Rings ("raw" serial ports) * UDP/IP broadcast (ethernet, etc) From Debian 3.0r0 APT

2. n. 1. The signal emitted by a Level 2 Ethernet transceiver at the end of every packet to show that the collision-detection circuit is still connected. 2. A periodic synchronization signal used by software or hardware, such as a bus clock or a periodic interrupt. 3. The `natural' oscillation frequency of a computer's clock crystal, before frequency division down to the machine's clock rate. 4. A signal emitted at regular intervals by software to demonstrate that it is still alive. Sometimes hardware is designed to reboot the machine if it stops hearing a heartbeat. See also breath-of-life packet. From Jargon Dictionary