What is Corosync in Pacemaker?

What is Corosync in Pacemaker?

Corosync is an open source program that provides cluster membership and messaging capabilities, often referred to as the messaging layer, to client servers. In essence, Corosync enables servers to communicate as a cluster, while Pacemaker provides the ability to control how the cluster behaves.

What is cluster stack?

Philosophy. Stacking connects two or more (up to 9) switches through a stack cable to so that physically separate switches form one logical switch. The stack of switches will be managed as one and having one management IP address.

What is Corosync in Redhat Cluster?

Corosync: Corosync is an opensource cluster engine which communicates with multiple cluster nodes and updates the cluster information database (cib. In previous redhat cluster release, “cman” was responsible for cluster interconnect, messaging and membership capabilities.

How are Pacemaker clusters set up?

The broad steps for the cluster configuration include:

1. Install Pacemaker packages on both nodes of the cluster.
2. Create the HACLUSTER user ID with.
3. Enable and start the pcs services.
4. Authenticate pcs with hacluster user.
5. Create the cluster.
6. Start the cluster.
7. Enable the cluster to auto-start after reboot.

What is Corosync ring?

Corosync is the messaging layer inside your cluster. It is responsable for several things like: Cluster membership and messaging thanks to the Totem Single Ring Ordering and Membership protocol. Quorum calculation. Availability manager.

What is Totem in Corosync?

Corosync uses the totem protocol for “heartbeat” like monitoring of the other node’s health. A token is passed around to each node, the node does some work (like acknowledge old messages, send new ones), and then it passes the token on to the next node. This goes around and around all the time.

What are the advantages of clustering vs stacking?

It is easier to be configured for stack since it can automatically recognize new stack member, while in a cluster, you have to manually add a device to be the switch cluster. The management of stack members depends on a single configuration file. While cluster members have separate and individual configuration files.

What is a switch cluster?

A switch cluster is a set of up to 16 connected, cluster-capable Catalyst switches that are managed as a single entity. The Switch in the cluster use the Switch clustering technology so that you can configure and troubleshoot a group of different Catalyst desktop Switch platforms through a single IP address.

What is Pacemaker high-availability?

Pacemaker is a high-availability cluster resource manager. It achieves maximum availability for your cluster services (a.k.a. resources) by detecting and recovering from node- and resource-level failures by making use of the messaging and membership capabilities provided by Corosync.

How do you set up a high-availability cluster?

To configure a high-availability cluster, you store shared files on network storage. Then, you configure multiple servers, set each server to access the same files and database, and configure a load balancer to distribute the traffic between the servers.

How do I install a high-availability cluster?

Steps involved to configure two node High Availability Cluster:

1. Install and Configure the Apache webserver (httpd Packages) on both nodes.
2. Enable the repo for High Availability Packages from ISO Image if needed or use public repos.
3. Install High Availability Cluster on both nodes.
4. Configure High Availability Cluster.