Virtualization administrators looking to take advantage of the KVM platform and one of the many KVM management tools should consider virt-manager due to its maturity and GUI-enabled ease of use.
KVM is a virtualization architecture for Linux distributions -- supported by Red Hat and Canonical -- that is free and open source. The available KVM management tools are not yet as elaborate or extensive as those for other virtualization platforms.
Many administrators manage KVM from the command line with virsh, which is a powerful tool with useful automation capabilities.
Virtual Machine Manager, otherwise known as virt-manager, is another option. Virt-manager is one of the most popular KVM management tools available. It's easy to install and is most reliable on a Linux-based system with a working desktop UI, but will also work on macOS and Windows
Advantages of virt-manager
Virt-manager manages KVM guests within a GUI. Start by connecting to a KVM host or hosts by adding connections.
Once you connect to a host, you can manage various host components, such as networking and storage. The most significant benefit of virt-manager is the ability to create, edit, start and stop existing VMs. You also have the ability to connect to the VM console, which uses the simple protocol for independent computing environments.
The GUI removes the complexity of traditional, command-line-based management that other KVM management tools have. It provides an interactive console to perform OS installations and other console operations. Virt-manager also gives you the ability to view real-time performance metrics for VMs and host utilization metrics.
Install virt-manager and create VMs
Virt-manager is included in most Linux distribution repositories. Install it with the following commands:
Debian/Ubuntu -- sudo apt install virt-manager
Fedora -- sudo dnf install virt-manager
CentOS -- sudo yum install virt-manager
To create a new VM using virt-manager, right-click on a host and select New. Provide a name for the VM. Select the installation media -- ISO or CD-ROM -- and then select the OS type. After that, select the memory and CPU requirements, as well as the hard drive requirements.
After you define the above requirements, your new VM will begin to install.
Delete and troubleshoot VMs
Deleting a VM is as easy as creating a new VM. Start by shutting down the VM. Highlight the VM, and then select delete. It will ask you to confirm the deletion of the associated disk.
Troubleshooting VMs is another advantage virt-manager has over other KVM management tools. Virt-manager has a console interface that each VM can connect to, which enables easy troubleshooting. For example, if you're having networking issues and receive reports that a VM became unreachable, virt-manager can help you discern potential causes.
To troubleshoot, examine the VM properties to ensure it is connected to a valid network on the host. Right-click the VM, select VM details and validate that the network interface card connection is attached to an applicable network on the host.
To troubleshoot other issues, open a console session and right-click on the VM, select console, and log in to the VM. Once you're logged in, you can perform basic network checks, such as validating an IP address. If that checks out, ping the gateway and make sure that a proper gateway is defined. You can then check the host-based firewall, which might have a misapplied rule that affects incoming communications. If this is the cause, you can remove the rule and re-establish communications. You can do all of this troubleshooting within virt-manager.
Virt-manager is one of the most mature KVM management tools available that uses a GUI. It's a powerful tool worth experimentation. Its ease of use and maturity could make it an essential part of your KVM management repertoire.