How to configure a highly available virtualization environment on Linux

How to configure a highly available virtualization environment on Linux

Overview:
With the continuous development of virtualization technology, more and more enterprises are beginning to adopt virtualization technology to improve IT resource utilization. efficiency and reliability. In the Linux operating system, we can configure a highly available virtualization environment to ensure that when a physical server fails, the virtual machine can be seamlessly migrated to another working server. This article will introduce how to configure a highly available virtualization environment on Linux, and attach code examples.

1. Install virtualization software
   First, we need to install a reliable virtualization software, such as KVM (Kernel-based Virtual Machine). In most Linux distributions, KVM is already included in the kernel, so we just need to install some additional packages. Here are the commands to install KVM on common Debian and Red Hat series distributions:

Debian series:
$ sudo apt-get install qemu-kvm libvirt-clients libvirt-daemon-system bridge-utils virt-manager

Red Hat series:
$ sudo yum install qemu-kvm libvirt bridge-utils virt-manager

2. Create virtual machine
   In installation After completing KVM, we can use virt-manager to create and manage virtual machines. Open a terminal and run the following command to start virt-manager:

$ sudo virt-manager

In the virt-manager interface, we can click "Create a new virtual machine " to create a new virtual machine. Configure the virtual machine name, memory size, hard disk size and other parameters as needed.

3. Set up shared storage
   To achieve high availability, we need to set up shared storage so that virtual machines can be migrated between multiple physical servers. This can be achieved by using iSCSI (Internet Small Computer System Interface). The following are some common iSCSI server software installation commands:

Debian series:
$ sudo apt-get install targetcli

Red Hat series:
$ sudo yum install targetcli

After the installation is complete, we can use the targetcli command to create iSCSI shared storage. Here is an example:

$ sudo targetcli
/> backstores/block create storage /dev/sdb
/> iscsi/ create iqn.2020-01.com.example:storage
/> iscsi/iqn.2020-01.com.example:storage/tpg1/luns create /backstores/block/storage
/> exit

4. Configure high availability
   In this example, we will use Pacemaker and Corosync to achieve high availability. Pacemaker is an open source cluster management tool, and Corosync is used for communication in the cluster. Here are the commands to install these software on Debian and Red Hat series distributions:

Debian series:
$ sudo apt-get install pacemaker corosync fence-agents

Red Hat series:
$ sudo yum install pacemaker corosync fence-agents

After the installation is complete, we need to configure Pacemaker. Open a terminal and run the following command:

$ sudo crm configure

Use the following command to create a virtual ip resource and associate it to the virtual machine:

crm(live)# primitive virtual-ip ocf:heartbeat:IPaddr2 params ip="192.168.0.100" cidr_netmask="24" nic="eth0" op monitor interval="30s"
crm(live)# primitive virtual-machine ocf:pacemaker: VirtualDomain params hypervisor="qemu:///system" config="/etc/libvirt/qemu/some_guest.xml" op monitor interval="30s"
crm(live)# group vm-group virtual-ip virtual- machine
crm(live)# commit

5. Test high availability
   In order to test high availability, we need to manually shut down the physical server that is currently running the virtual machine. On another server that is working fine, we should see the VM successfully migrated to the new node and continue running. The following is the command to test on the terminal:

$ sudo virsh destroy some_guest
$ sudo virsh undefine some_guest

Before shutting down the virtual machine, you can use the following command to view The node where the virtual machine is located:

$ sudo crm status

Conclusion:
By configuring a highly available virtualization environment, we can ensure that when a physical server fails, the virtual machine can Seamlessly migrate to another working server. This article introduces how to use KVM, iSCSI, Pacemaker, and Corosync to configure a highly available virtualization environment on Linux, and provides corresponding code examples. I hope this article can be helpful to readers when configuring a highly available virtualization environment.

Reference link:

1. https://www.debian.org/
2. https://www.redhat.com/
3. https://help.ubuntu.com/community/KVM
4. https://www.linux-kvm.org/page/Main_Page

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