Frequently Asked Questions
Q: Where can I get Pacemaker?
A: Pacemaker ships as part of most common Linux distributions, including CentOS, Debian, Fedora, Gentoo, OpenSUSE, Red Hat Enterpise Linux, SUSE Linux Enterprise Server, Ubuntu, and their derivatives, so you can usually just launch your favorite package manager.
If all else fails, you can try installing from source.
Q: Is there any documentation?
A: Yes. You can find the set relevant to your version in our documentation index.
Q: Where should I ask questions?
A: The ClusterLabs mailing lists are usually the best place, as there is an active community with a wide range of experience, and the answers will be archived to benefit all users. There is also the #clusterlabs IRC channel on Libera for more immediate gratification, though with fewer participants.
Q: What kind of applications can I manage with Pacemaker?
A: Pacemaker has no direct intelligence about specific services. Instead, it relies on resource agents, which are small applications (often shell scripts) that provide a standardized, generic interface to particular services. This means that any service can be made highly available, using a script conforming to one of the supported standards: LSB ("init scripts"), OCF resource agents, and depending on the environment and options selected when Pacemaker was built, systemd units, upstart, and Nagios Plugins. The ClusterLabs resource-agents project provides a set of OCF agents for common services, and other projects provide additional agents.
Q: Do I need shared storage?
A: No. Pacemaker can manage shared storage, and there are fencing techniques that can utilize shared storage, but Pacemaker itself does not require it.
Q: Which cluster filesystems does Pacemaker support?
A: Pacemaker can support any filesystem with an appropriate resource agent. The resource-agents project provides agents for OCFS2 and GFS2. You can use these cluster filesystems with physical disks or network block devices such as DRBD.
Q: What does Pacemaker use for cluster quorum and communication?
A: Pacemaker relies on external software for cluster formation. Pacemaker 2.0.0 and above supports only Corosync version 2.0 or above for this purpose. Older Pacemaker versions additionally supported Heartbeat and Corosync 1 with either CMAN or the Pacemaker plugin.
Q: Does my cluster need fencing?
A: Yes.
Q: No, really, isn't fencing optional?
A: Fencing is the only way to recover from certain failure scenarios and ensure the integrity of your data by avoiding a "split-brain" situation. Although Pacemaker is technically able to function without fencing, organizations that provide commercial support generally require it, for good reason.
Q: How is Pacemaker configured?
A: Pacemaker uses XML as its native configuration format, but users do not have to deal with XML directly. Pacemaker provides low-level command-line tools for common tasks, and other projects provide more user-friendly, high-level command-line and graphical user interfaces.
Q: How do I synchronize the cluster configuration?
A: Any changes to Pacemaker's configuration are automatically replicated to other machines. The configuration is also versioned, so any offline machines will be updated when they return.
Q: Should I choose pcs or the crm shell as a high-level interface?
A: Arguably the best advice is to use whichever one comes with your distro. This is the one that will be tailored to that environment, receive regular bugfixes and feature in the documentation.
Of course, if you have a strong preference, you can build your favorite configuration tool from source if your distro doesn't ship it.
Q: What if my question isn't here?
A: See the getting help section and let us know!
