Configure High Avaliablity Cluster on Cent. OS 7 RHEL 7. High Availability cluster aka Failover cluster active passive cluster is one of the most widely used cluster types in the production environment. This type of cluster provides you the continued availability of services even one of the node from the group of computer fails. If the server running application has failed for some reason hardware failure, cluster software pacemaker will restart the application on another node. Mostly in production, you can find this type of cluster is mainly used for databases, custom application and also for file sharing. Fail over is not just starting an application it has some series of operations associated with it like mounting filesystems, configuring networks and starting dependent applications. Cent. OS 7 RHEL 7 supports Fail over cluster using the pacemaker, we will be looking here about configuring the apache web server as a highly available application. As I said, fail over is a series of operations, so we would need to configure filesystem and networks as a resource. For a filesystem, we would be using a shared storage from i. SCSI storage. Our Environment Configure High Availability Cluster on Cent. OS 7 Infrastructure. Cluster Nodes node. SCSI Storage server. All nodes are of Cent. OS Linux release 7. Core, running on VMware workstation. Install Debian Object In Virtualbox UbuntuBuilding Infrastructure i. SCSI shared storage Shared storage is one of the important resources in the high availability cluster, it holds the data of a running application. All the nodes in a cluster will have access to shared storage for recent data, SAN is the most widely used shared storage in the production environment here, we will configure a cluster with i. SCSI storage for a demonstration purpose. Here, we will create 1. GB of LVM disk on the i. SCSI server to use as a shared storage for our cluster nodes. Lets list the available disks attached to the target server using the command. Disk devsda 1. GB, 1. Linux. devsda. 2 1. Linux LVM. Disk devsdb 1. GB, 1. 07. 37. 41. From the above output, you can see that my system has a 1. GB of disk devsdb. Create an LVM with devsdb replace devsdb with your disk namerootserver pvcreate devsdb. FREE n lviscsi vgiscsi. This tutorial shows how to install and Configure OpenLDAP server on Ubuntu 16. We will also install the phpLDAPadmin webbased management tool. How to Install New Apple Desktop operating system macOS Sierra on VirtualBox. Install macOS Sierra 10. VirtualBox. Installing macOS on VirtualBox. Overview. VirtualGL is an open source package which gives any Unix or Linux remote display software the ability to run OpenGL applications with full 3D hardware. Creating i. SCSI target Install the targetcli package on the server. Once you installed the package, enter below command to get an i. SCSI CLI for an interactive prompt. Warning Could not load preferences file root. Copyright 2. 01. 1 2. Datera, Inc and others. For help on commands, type help. Created block storage object iscsisharedstorage using devvgiscsilviscsi. Install Debian Object In Virtualbox UsbCreated target iqn. Global pref autoadddefaultportaltrue. Created default portal listening on all IPs 0. Created Node ACL for iqn. Parameter authentication is now 0. Parameter generatenodeacls is now 1. Created LUN 0 0 mapping in node ACL iqn. Storage Objects 1. Gi. B write thru activated. Storage Objects 0. Storage Objects 0. Storage Objects 0. Targets 1. o iqn. TPGs 1.    o tpg. ACLs 1.      o iqn. Mapped LUNs 1.         o mappedlun. LUNs 1.      o lun. Portals 1.        o 0. OK. o loopback. Targets 0. Last 1. 0 configs saved in etctargetbackup. Configuration saved to etctargetsaveconfig. Global pref autosaveonexittrue. Last 1. 0 configs saved in etctargetbackup. Configuration saved to etctargetsaveconfig. Enable and restart the target service. Configure the firewall to allow i. SCSI traffic. rootserver firewall cmd permanent add port3. Configure Initiator Its the time to configure cluster nodes to make a use of i. SCSI storage, perform below steps on all of your cluster nodes. Discover the target using below command. Edit below file and add iscsi initiator name. Initiator. Nameiqn. Login to the target. T iqn. Logging in to iface default, target iqn. Login to iface default, target iqn. Restart and enable the initiator service. Setup Cluster Nodes Go to all of your nodes and check whether the new disk is visible or not. In my case, devsdb is the new disk. Disk devsda 1. GB, 1. Linux. devsda. 2         1. Linux LVM. Disk devsdb 1. Game Theory Strategy Philip Strafing Video. GB, 1. 07. 33. 22. On any one of your node Ex, node. LVM using below commandsrootnode. FREE vgapache. rootnode. Now, go to your remaining nodes and run below commandsrootnode. Finally, verify the LV we created on node. Ex. node. 2 using below command. You should see devvgapachelvapache on all your nodes. Output Logical volume. LV Path devvgapachelvapache. LV Name lvapache. VG Name vgapache. LV UUID UDux. VKXO pjg. X J2m. E M0. U0 EO4r q. P2ziq. LV Write Access readwrite. LV Creation host, time node. LV Status available. LV Size 1. Gi. B. Current LE 2. Segments 1. Allocation inherit. Read ahead sectors auto. Block device 2. Make a host entry on each node for all nodes, the cluster will be using the host name to communicate each other. Perform tasks on all of your cluster nodes. Install cluster packages pacemaker on all nodes using below command. Allow all high availability application on the firewall to have a proper communication between nodes, you can skip this step if the system doesnt have firewalld installed. Use below command to list down the allowed applications in the firewall. Set password for hacluster user, this is cluster administration account. We suggest you set the same password for all nodes. Start the cluster service, also, enable it to start automatically on system startup. Remember to run the above commands on all of your cluster nodes. Cluster Creation Authorize the nodes using below command, run the command in any one of the node. Username hacluster. Authorized. node. Authorized. Create a cluster. Shutting down pacemakercorosync services. Redirecting to binsystemctl stop  pacemaker. Redirecting to binsystemctl stop  corosync. Killing any remaining services. Removing all cluster configuration files. Succeeded. node. 2. Succeeded. Starting cluster on nodes node. Starting Cluster. Starting Cluster. Synchronizing pcsd certificates on nodes node. Success. node. 2. Success. Restaring pcsd on the nodes in order to reload the certificates. Success. node. 2. Success. Enable the cluster to start at the system startup, else you will need to start the cluster on every time you restart the system. Cluster Enabled. node. Cluster Enabled. Use below command to get the status of the cluster. Cluster Status. Last updated Fri Mar 2. Last change Fri Mar 2. Stack corosync. Current DC node. Online node. 1. Online. Online. Run the below command to get a detailed information about the cluster including its resources, pacemaker status, and nodes details. Cluster name itzgeekcluster. WARNING no stonith devices and stonith enabled is not false. Last updated Fri Mar 2. Last change Fri Mar 2. Stack corosync. Current DC node. Online node. 1. Full list of resources. Online. node. 2. itzgeek. Online. corosync activeenabled. Fencing Devices The fencing device is a hardware software device which helps to disconnect the problem node by resetting node disconnecting shared storage from accessing it.