KVM virtualization supports a variety of disk image formats. The most common disk formats are qcow2 and raw disk image. qcow2 is the most versatile and versatile virtual disk format that provides a set of useful functions, such as 128-bit AES encryption, support for multiple snapshots, and zlib compression. To expand or resize the disk space of the KVM virtual machine to accommodate more books or create additional partitions, use the following methods.

First check the current disk size:

virsh dominfo <vm-name>

To stop the VM:

virsh shutdown <vm-name>

Extended disk file:

qemu-img resize /path/to/vm-disk.qcow2 +<new-size>

<new-size> indicates a specific value. For example, 30G indicates an increase of 30GB, and +30GB indicates an increase of 30GB on the original basis.

Edit the virtual machine's XML configuration file to reflect the new disk size:

virsh edit <vm-name>

In the XML configuration, find the disk section to ensure that the bus and dev properties of the target match the virtual machine Settings. You generally do not need to change this section unless you change the way the disks are connected.

To start the VM:

virsh start <vm-name>

Extended file systems, for ext4 file systems:

resize2fs /dev/sda1

For xfs file systems:

xfs_growfs /

For Btrfs file systems:

btrfs filesystem resize max /

Can be expanded to the maximum available space. When performing the preceding steps, ensure that there is a backup of the image file to prevent problems. Expanding the disk size may take some time, depending on the amount of additional space and the performance of the disk. Ensure that the virtual machine configuration and host have sufficient resources to support larger disks.

Monitoring KVM VM disk usage is critical to managing resources and ensuring performance. virsh is one of the KVM management tools that can be used to view the disk usage of a VM.

virsh domdf --persistent <vm-name>

The preceding command displays detailed information about all disks on the VM, such as disk size and usage.

Get disk image file information:

qemu-img info /path/to/vm-disk.qcow2

Inside the virtual machine, use the standard df command to view the disk usage of the file system:

df -h

The disk usage of the file system is displayed in an easy-to-read format, such as MB, GB. You can also use tools such as GNOME Disk Usage Analyzer or KDE Disk Usage Analyzer to monitor disk usage. Or you can use monitoring systems such as Nagios, Zabbix, and Prometheus to monitor the disk usage of KVM VMS. These systems can be configured with alarms to notify administrators when disk usage reaches a certain threshold.

Log analysis tools such as ELK Stack (Elasticsearch, Logstash, Kibana) can also be used to analyze log data for disk usage and create visual dashboards.

You can also set up periodic reports, run the disk usage report script periodically using the cron job, and send the report to the administrator's mailbox.