Corosync is a framework for reliable cluster communications, the "lower" half of the high availability software stack. (The "upper" half is cluster resource management, such as Pacemaker).

We have collected multiple years of experience with setting up and maintaining Corosync-based clusters. We're actively involved in its development by sending bug reports and patches. We're frequently in touch with the Corosync core developers.

If you're looking for help with Corosync, we will deliver.

What's it good for?

Corosync provides a reliable communications layer for high availability clusters. It ensures that cluster nodes can send and receive messages over multiple, redundant communication paths ("rings"). Corosync supports multiple transports, such as multicast UDP, unicast UDP, and native InfiniBand.

Corosync runs on on all recent Linux distributions. It's the standard cluster communication layer on SLES, RHEL, Ubuntu and Debian GNU/Linux.

How is it used?

The Pacemaker cluster resource management framework uses Corosync as its preferred communications layer. Corosync is also the only supported comm layer in CMAN clusters, also known as Red Hat Cluster Suite or, currently, Red Hat Enterprise Linux High-Availability Add-On.

Corosync is also the communications layer for Sheepdog, a distributed storage platform for KVM, Proxmox VE (as of version 2), and the Apache Qpid cross-platform messaging system.

How is it related to OpenAIS?

Corosync grew out of the OpenAIS project, a 2006 implementation of the Service Availability Forum's standard Application Interface Specification (AIS). The project later split into an infrastructure platform (Corosync) and an interface/plugin layer which confusingly retained the name OpenAIS.

Development on OpenAIS has now practically ceased as applications switched from invoking the AIS-compatible layer to making direct Corosync library calls. Corosync development continues to thrive.

How is it related to Heartbeat?

Corosync shares no code with another cluster communications layer, Heartbeat. The Pacemaker cluster resource manager currently supports both stacks (although it prefers Corosync), and Heartbeat/Pacemaker clusters can even switch to Corosync/Pacemaker with no service interruption.

Other cluster resource managers, such as CMAN (Red Hat Cluster), support Corosync exclusively.

If you're stuck with Corosync, we can help you out. We can offer a wide array of Corosync consulting services. Talk to one of us within the next 15 minutes. Ask The Expert Now!