Storage management within a virtualized environment is key to ensuring that VMs run as reliably and efficiently as possible. KVM (Kernel-based Virtual Machine) is a robust environment management platform for virtualized resources. One of the key concepts of this platform is storage pools. Storage pools are holding sites for the virtual disk images and the virtual machine’s required resources. Storage pools enable the administrator to plan, assign, and manage the storage on a scalable and extensible basis. Libvirt uses storage pools and volumes to offer physical host storage management.

A KVM storage pool is a virtual storage device that maps to a physical storage device or set of devices. Administrators can use storage pools to manage the allocation of storage to virtual machines and the simplification of rising virtual workload demands.

Why Are Storage Pools Important?

Storage pools are a crucial part of virtualized infrastructure due to the following reasons:

• Centralized Management: Storage pools allow you to manage disk images of VMs, ISOs and so forth from a central location. It is less complicated and easier than the management of each VM’s storage.
• Scalability: Storage pools make scaling the virtualization environment easy. The storage capacity can be expanded easily or new storage technology brought into the environment.
• Performance Optimization: Pools of various types provide varying levels of performance. For instance, LVM and iSCSI pools provide quick access to the storage, a requirement for applications that are sensitive to the performance level.
• Flexibility: KVM supports a wide range of storage pool types, from basic directory-based pools to advanced ones like Ceph and GlusterFS. It offers the option of choosing the storage solution that most appropriately matches your requirement and budget.
• High Availability and Redundancy: Storage pools such as GlusterFS and Ceph offer native redundancy and high availability features giving maximum availability of your VMs even in the face of hardware failure.

Supported Storage Pool Types

KVM supports several storage pool types, each of which will suit various situations and needs. This chapter covers the most common types of storage pools, how they are set up, and a set of useful examples.

This chapter focuses on seven primary types of storage pools within the KVM ecosystem:

1. Directory Storage Pool
2. Disk Storage Pool
3. Partition Storage Pool
4. LVM (Logical Volume Manager) Storage Pool
5. Network Filesystem Storage Pool
6. iSCSI Storage Pool
7. ZFS Storage Pool
8. RBD (Ceph) Storage Pool (to be addressed with infrastructure setup)
9. GlusterFS Storage Pool (optional, TBD)

Depending on the use case, each of these pool kinds has particular benefits; moreover, they can be developed and controlled in several ways. Giving complete control over pool creation, the most thorough and flexible approach is the Virsh CLI. One more user-friendly choice with a simple, graphical approach is the Cockpit GUI. Finally, Virt-Manager offers a user-friendly GUI as well, although for some jobs it is less desired than Cockpit.

Although the configuration of these storage pools will be the main emphasis of this chapter, it is noteworthy that the preparation and installation of the server-side storage—that is, configuring NFS, iSCSI, or Ceph servers—falls outside the purview of this guide. Though they are not covered in this chapter, these subjects will be connected to pertinent materials offering detailed instructions on configuring the necessary outside services.

By the end of this chapter, you will have a thorough knowledge of how to build and control KVM storage pools using several techniques and tools, so allowing you the flexibility to select the best approach for your virtualized infrastructure.

Configuration Methods

KVM offers a variety of tools and interfaces for configuring and administering storage pools, and operators have a choice of the most suitable one for their workflow and experience. There are three main methods of configuring that this chapter addresses:

Virsh CLI

Virsh is a powerful and handy command-line utility for the management of a KVM virtualization environment. It belongs to the libvirt utility suite and provides a command line for the management of storage pools and virtual machines as well as the virtualization infrastructure. The use of virsh becomes particularly suitable for the needs of those system administrators who have a strong inclination towards using a terminal-based environment or who need the ability to automate tasks through the use of scripts, thus optimizing the level of work productivity.

Pros

• Highly detailed and granular control over configurations.
• Suitable and apt for scripting tasks and automation processes.
• There is no dependence or reliance on graphical interfaces at all.

Cons

• This method has proven to be a much steeper learning curve for beginners.
• Because of it’s CLI constriction, it requires familiarity with command-line syntax.

Virsh CLI will be our focus and main method for storage pool configuration. The reason behind this is that it provides the most comprehensive and detailed approach for configuration.

Cockpit UI

Cockpit is a modern and cutting-edge web-based interface specially designed to enable the smooth and efficient management of Linux servers, along with managing KVM virtualization environments with ease. The feature-rich tool provides a very intuitive and user-friendly graphical console, which makes it an easy task to configure storage pools and create virtual machines, while also offering an effortless means to manage other vital resources. Most server administrators usually find Cockpit much simpler and easier to use compared to Virt-Manager, which results in a strong preference for Cockpit because of its ease and simplicity, especially for those who prefer a graphical user interface-based solution for their day-to-day operational activities.

Cockpit also has it’s advantages and disadvantages.

Pros

• It’s intuitive and very easy to use, making it accessible even for the most inexperienced and new players.
• There is absolutely no need whatsoever to go about the process of installing any supplementary software since Cockpit comes pre-installed and available on a very broad range of Linux distributions.
• Enables remote access by taking advantage of the features provided by a web browser.

Cons

• Cockpit is not as complete or detailed as the Virsh Command Line Interface, especially in managing complex configurations and settings.
• Depends on a web browser for functionality and needing an active network connection to retrieve resources and information. We will discuss here the use of Cockpit as a further choice over the traditional Virsh command line.

In this chapter, Cockpit will be used as an alternative to Virsh CLI for users who prefer a graphical interface.

Virt Manager

Virt-Manager is a feature-rich, desktop-oriented graphical application expressly aimed at facilitating the efficient management of KVM virtualization infrastructures. This feature-rich application offers an extensive and intuitive interface through which users can readily configure and manage storage pools, virtual machines, and other vital resources in the virtualization infrastructure with ease. Despite its functional similarities with Cockpit, Virt-Manager is a standalone application, and as such, it requires a dedicated installation on a supported desktop environment in order for users to have access and make use of its capabilities to the fullest.

Pros

• Provides a wide variety of features that are designed especially for effective management and monitoring of virtualization resources within a cost-effective way.
• Suitable for administrators who prefer a desktop-based GUI.

Cons

• The procedure requires the installation of additional software components.
• For new players, it’s less intuitive and less user-friendly compared to Cockpit.

In this specific chapter, we are going to use Virt-Manager as another graphical user interface-based method. Nevertheless, it should be mentioned that wherever possible, there is going to be a strong preference for Cockpit over others.

Choosing the right configuration method

The choice of any specific configuration technique depends on several considerations such as your own preferences, your level of experience, and the special and specific demands that are typical in your setup. The following might help you make a choice:

• Use Virsh CLI if you need detailed control, prefer working in the terminal, or want to automate tasks.
• If you’re leaning towards a simple and easy-to-use web-based user interface, then it’s very much recommended that you take advantage of Cockpit. Particularly if you want to access your computing environment on a remotely from anywhere.
• In case you have a preference for a desktop GUI and are in need of additional features, then the use of Virt-Manager is recommended.

🌍 Whether at work or on the go, access Mastering KVM Virtualization anytime, in the book you will learn:

• Supported Storage Pool Types
• Storage Management Using Virsh CLI
• Storage Management using Cockpit UI
• Storage Management using Virt-Manager