Corosync provides the communication of the cluster and participates in the calculation of the quorum in many Linux environments, including Proxmox VE. An incident Corosync must be treated as a cluster and network problem: link status, latency, packet loss and consistency of configuration are decisive.
Simple definition
Corosync provides communications and quorum many Linux hilariously, including Proxmox.
Technical definition
Corosync provides communications and quorum Many Linux 2007-11-13, including Proxmox. In the business environment, its configuration must be consistent with the network architecture, security policies and capabilities of the equipment concerned.
Pass correction Corosync
After correction, check that all nodes see the same membership of the Cluster and that the quorum Stay stable for several minutes. On Proxmox, check again pvecm status, links Corosync and the logs around the incident. A network correction must be validated under normal cluster load, not just by a few pings.
What is it used for?
maintain communication between nodes.
Practical example
Proxmox nodes exchange their state via corosync.
How to check Corosync on a Proxmox cluster?
On Proxmox VE, start with pvecm status to verify the quorum and the view of the cluster. Complete with corosync-cfgtool -s for the status of links and corosync-quorumtool -s when available. Compare the number of expected nodes, the status of the links and the addresses configured before changing the configuration Corosync.
- Controlling quorum.
- Check links Corosync.
- Test latency and loss between knots.
- Compare configuration across the entire cluster.
Common issues
Simple IP connectivity does not guarantee a healthy cluster. latency, loss of packages, a MTU inconsistent, a wrong link address, a firewall or a partially isolated node may degrade Corosync. Avoid forcing the quorum as a first response: this action may increase the risk of conflicting decisions between nodes if the network cause is not understood.
FAQ — Corosync and quorum
Corosync Is it specific to Proxmox?
No. Corosync is used by different stacks of Linux cluster; Proxmox VE uses it for communication between nodes.
One ping does he prove that Corosync Does it work?
No. The cluster also depends on stability, latency, packet loss and link configuration.
What it means to lose the quorum ?
The cluster no longer has the number of votes needed to make certain decisions safely; it must be looked for before circumventing protection.