Thin-provisioning Virtual Machine Drive Images with virt-sparsify (with examples)

Use Case 1: Creating a Sparsified Compressed Image without Snapshots

Code:

virt-sparsify --compress path/to/image.qcow2 path/to/image_new.qcow2

Motivation:

The motivation behind this use case is to create a new sparsified and compressed image from an existing unsparsified image. By doing this, we can reduce the disk space consumed by the virtual machine drive image.

Explanation:

• --compress: This argument is used to compress the sparsified image. The compression helps in reducing the disk space occupied by the image file.
• path/to/image.qcow2: This is the path of the original unsparsified image file that needs to be sparsified.
• path/to/image_new.qcow2: This is the path of the new sparsified and compressed image file that will be created.

Example Output:

Sparsifying disk /path/to/image.qcow2 -> /path/to/image_new.qcow2:
Output disk: /path/to/image_new.qcow2
Disk size: 10G
Sparse 0->4G
Sparse 4G->10G

The command successfully sparsifies the original image image.qcow2 and creates a new compressed image image_new.qcow2. The output indicates the path and size of the new image, as well as the sparsification details.

Use Case 2: Sparsifying an Image In-Place

Code:

virt-sparsify --in-place path/to/image.img

Motivation:

The motivation behind this use case is to sparsify an image without creating a new image file. This can be useful when we want to free up disk space on the host system by converting an unsparsified image to a sparsified one.

Explanation:

• --in-place: This argument is used to perform the sparsification operation on the original image file itself, instead of creating a new image file.
• path/to/image.img: This is the path of the original unsparsified image file that needs to be sparsified.

Example Output:

Sparsifying disk /path/to/image.img:
Disk size: 20G
Sparse 0->10G
Sparse 10G->20G

The command successfully sparsifies the original image image.img, without creating a new image file. The output indicates the size of the sparsified disk and the sparsification details.

Conclusion

Using the virt-sparsify command, we can efficiently create sparsified and compressed virtual machine drive images or perform in-place sparsification. By reducing disk space usage, these operations can help optimize storage utilization and improve system performance. However, it is important to note that these operations should only be performed on offline machines to avoid any potential data corruption.