Note Pacemaker is the Project Successor of "Heartbeat version 2"
If you are looking for documentation and information for the "Version 2" heartbeat, you should really be reading the Pacemaker home page at http://clusterlabs.org.
If you are stuck with Heartbeat 2.1.3 or Heartbeat 2.1.4, the best fitting Documentation is probably that for Pacemaker 0.6, which can also be found on the Pacemaker Documentation page
Quoting the first paragraph from v2 (in this wiki):
Heartbeat 2.1.4 was the last release to contain the CRM or "Version 2 Resource Manager" and since then all development and maintenance is performed as part of the Pacemaker project and all CRM code has been removed from Heartbeat.
For more details on Pacemaker, including latest versions, installation details and documentation, please visit http://clusterlabs.org.
Linux-HA provides sophisticated high-availability (failover) capabilities on a wide range of platforms, supporting several tens of thousands of mission critical sites all over the globe. A few of these are documented in our success stories page.
Linux-HA is the oldest, most capable, and best-tested open source HA solution available and has the largest associated community. By project policy, it always compiles with no warnings, and no faults found by a static analysis tool. Source code is periodically subjected to scrutiny by security experts.
It provides monitoring of cluster nodes, applications, and provides a sophisticated dependency model with a rule-based resource placement scheme. When faults occur, or a rules change occurs, the user-supplied rules are then followed to provide the desired resource placement in the cluster.
It is generally at least as capable and easy-to-use as most commercial clustering offerings such as Veritas VCS, SunCluster, LifeKeeper, ServiceGuard and others.
- most services require no application scripts for basic management.
Full-featured GUI - for configuring, controlling, and monitoring HA services and servers
CIM (Common Information Model) support for industry-standard Systems Management support
Integrated support for LVS load balancing
Integrated and easy-to-use support for ClusterIP load distribution
Integrated and easy-to-use support for DRBD high-integrity host-based data replication
Linux-HA is used on a huge number of platforms, ranging from ARM processors through mainframes. We test extensively on ia32, powerPC, and System Z (mainframe) platforms (8 hours to 8 days), and perform basic testing of each release on every platform supported by SUSE Linux:
Linux-HA is portable to many platforms, and we treat portability bugs seriously. Patches to fix portability bugs are welcomed.
Linux-HA has no special shared disk requirements.
It supports (at least) the following data sharing configurations:
replication (DRBD, or application-specific)
SCSI RAID controllers supporting clustering (IBM ServeRAID, ICP Vortex)
The only requirements we have on shared disk is that it support mount and umount. More specifically, it does not rely on SCSI reservations (or their equivalent).
Linux-HA is highly portable, and runs on many POSIX-like platforms. It is best supported (and works best) on Linux - virtually any version. The build system creates RPMs and Debian packages automatically, and it is also integrated into the Gentoo Linux build system, among others. Linux-HA is provided natively with SUSE Linux, Mandriva Linux, TurboLinux, Red Flag Linux, Debian, Gentoo and a few other Linux distributions, and is a standard part of many Linux-based products.
It also works on FreeBSD and Solaris and the Mac's OS/X.
Heartbeat will run in whatever memory your OS and application needs plus about 16 megabytes more. Although it is relatively lightweight, Linux-HA locks certain core components into memory.
The RPMs document this best. And, if you don't want to install some of these libraries, then many of these dependencies can be automatically eliminated by rebuilding from source. The only two slightly unusual mandatory dependencies are glib2, and libnet >= 1.1. Use of the GUI or CIM requires the GNU TLS libraries.
The STONITH plugins create a variety of dependencies on the libraries they need - but you don't actually need most or any of them for any given installation, and Autoconf will not create modules you don't have the libraries for.
Linux-HA will run on any kernel that doesn't have a major scheduler bug. For Linux, that means basically anything but Red Hat Linux kernels 2.4.18-2.4.20.
It has no kernel dependencies, drivers, file system requirements, or other hooks.
There is no fixed maximum number of nodes allowed beginning in Version 2.0. We have tested it with up to 16 nodes. Reports occasionally trickle in of people using it with more than double that number.
Heartbeat currently comes with the following adminstrative tools:
haclient - Graphical User Interface for configuring, controlling and monitoring cluster
crmadmin - provide node related details
cibadmin - allows the current configuration to be queried and modified
crm_verify - checks a configuration is valid
crm_mon - provides the current cluster status in text or HTML
crm_resource - query and modify all things related to cluster resources/services
crm_standby - control a node's standby status (ability to run resources)
cl_status - provides low-level node-centric connectivity information.
Linux-HA can support virtually any application that can withstand a crash and be restarted robustly every time, and which can somehow access a good copy of its state data from the machines that need to run the service. See the section on Data Sharing Arrangements for details of common methods for sharing application state.
People do a huge variety of things with Linux-HA. If you want it, someone has probably already done it. It supports most applications immediately without writing any scripts.
Linux-HA provides configurable automated notification whenever resources move from one machine to another, through the MailTo resource agent. You can easily write your own if you don't like ours. Additionally, you can run an SNMP agent which will send out SNMP traps when nodes fail, or monitor and control it through the Common Information Model (CIM) cluster model.
Linux-HA's processor usage is usually negligible, typically much less than 1 percent. If you configure ultra-fast failover times (< 1 second), then this amount will go up with the required faster heartbeat rates.
This is a difficult question to answer since it depends on where you start. As a rule, good HA systems add about one "9" to your system's availability, when appropriately configured. This general rule applies to Linux-HA as well. That is, if your pre-HA clustering availability was 99.9%, then the resulting availability of your system ought to be something like about 99.99%. One can improve on this through good administrative procedures and higher degrees of redundancy.
When properly configured, Linux-HA can detect failure in less than a second. It is fairly common that people configure a failure detection time of a small number of seconds.
Linux-HA release 2 comes with web-based and command-line-based cluster monitoring capabilities showing most aspects of current cluster status.
You can also monitor its basic capabilities through SNMP using your favorite SNMP-enabled systems management tool or through our cl_status tool.
CIM cluster model support is also provided for leading edge systems management support.
Linux-HA does not provide one at this time, but you could add one easily if you felt strongly about it. It would take around 30 lines of shell script.
Since ssh does such a good job, and the security implications are significant, we haven't yet been motivated to provide such a facility.
You can remotely administer nodes with ssh, or the GUI. Resource configuration can be accomplished on any node in the cluster. CIM administration can perform a wide variety of management operations on any cluster node.
We support rebooting through STONITH plugins which we provide. Appropriate hardware is required.