To add the service as a resource, use the pcs resource create command. Provide a name for the service. To invoke the Dummy resource agent, a notation ocf:pacemaker:Dummy is used to specify that it conforms to the OCF standard, that it runs in the pacemaker namespace and that the Dummy script should be used. If you were configuring a heartbeat monitor service for an Oracle Database, you might use the ocf:heartbeat:oracle resource agent. The resource is configured to use the monitor operation in the agent and an interval is set to check the health of the service.
In this example we set the interval to s to give the service some time to fail while you are demonstrating failover. By default, this is usually set to 20 seconds, but may be modified depending on the type of service and your own environment.
As soon as you create a service, the cluster attempts to start the resource on a node using the resource agent's start command. You can see the resource start and run status by running the pcs status command:. You should see the service restart on the alternate node. You can try to reboot the node where the service is running to see that failover also occurs in the case of node failure.
Note that if you have not enabled the corosync and pacemaker services to start on boot, you may need to start the service on the node that you have rebooted, manually.
For example:. Fencing or stonith is used to protect data when nodes become unresponsive. If a node fails to respond, it may still be accessing data. To be sure that your data is safe, you can use fencing to prevent a live node from having access to the data until the original node is truly offline.
To do this, you must configure a device that can ensure that a node is taken offline. There are a number of fencing agents available that can be configured for this purpose.
In general, stonith relies on particular hardware and service protocols that can force reboot or shutdown nodes physically to protect the cluster. In this section, different configurations using some of the available fencing agents are presented as examples. Note that these examples make certain presumptions about hardware and assume that you are already aware of how to set up, configure and use the hardware concerned. The examples are provided for basic guidance and it is recommended that you also refer to upstream documentation to familiarize yourself with some of the concepts presented here.
Before proceeding with any of these example configurations, you must ensure that stonith is enabled for your cluster configuration:.
After you have configured stonith , you can check your configuration to ensure that it is set up correctly by running the following commands:. To check the status of your stonith configuration, run:.
Intelligent Platform Management Interface IPMI is an interface to a subsystem that provides management features of the host system's hardware and firmware and includes facilities to power cycle a system over a dedicated network without any requirement to access the system's operating system. This device uses electrical pulses to prompt the heart to beat at a normal rate.
Pacemakers are used to treat arrhythmias ah-RITH-me-ahs. Arrhythmias are problems with the rate or rhythm of the heartbeat. What is pacemaker Corosync? Corosync is an open source program that provides cluster membership and messaging capabilities, often referred to as the messaging layer, to client servers.
How many types of clusters are there in Linux? What is a cluster in Linux? A Linux cluster is a connected array of Linux computers or nodes that work together and can be viewed and managed as a single system. A server cluster is a group of linked servers that work together to improve system performance, load balancing and service availability. What is DRBD cluster? DRBD is a distributed replicated storage system for the Linux platform. DRBD is traditionally used in high availability HA computer clusters, but beginning with DRBD version 9, it can also be used to create larger software defined storage pools with a focus on cloud integration.
What is cluster in Linux Redhat? Red Hat Cluster Suite RHCS is an integrated set of software components that can be deployed in a variety of configurations to suit your needs for performance, high-availability, load balancing, scalability, file sharing, and economy.
What is PCS cluster? Set the password for the hacluster user, again on both nodes, that is created during the package installation. This user will be used to authenticate to the other cluster nodes and to perform actions on the cluster:. On node1 , authenticate as the hacluster user:. Generate and synchronize the corosync configuration on node1 :.
Now that the cluster is up and running, we can create our cluster resources. Once the resources are created, we can set resources constraints to ensure that the IP address always starts before the Apache HTTP server and that the two resources always run together on the same node.
Add an IP address resource to the cluster on node1 :. Set a colocation constraint on node1 , to ensure that the cluster resources run on the same node:. Again, on node1 , set an order constraint to ensure that the cluster resources start in the correct order:. Validate the status of the cluster resources on node1 :. Now we have successfully configured a failover cluster using Pacemaker! Userpage tools. Categories Pacemaker. Namespaces Page Discussion. Page actions View View source History More.
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