The value set by Filesystem Overhead does not take effect

[silenceper]

What happened:

What you expected to happen:
I think the virtual size of this img file should be less than 200G;

In addition, I verified that this overhead parameter will only take effect during resize, and will not take effect for the initial creation.

How to reproduce it (as minimally and precisely as possible):
Steps to reproduce the behavior.

Additional context:
Add any other context about the problem here.

Environment:

• KubeVirt version (use virtctl version): 1.1.1
• Kubernetes version (use kubectl version): 1.24
• VM or VMI specifications: N/A
• Cloud provider or hardware configuration: N/A
• OS (e.g. from /etc/os-release): N/A
• Kernel (e.g. uname -a): N/A
• Install tools: N/A
• Others: N/A

[xpivarc]

@akalenyu can you have a look?

[silenceper]

Please confirm whether this is a bug or a design flaw; if it is confirmed to be a bug, I can submit a PR to fix it.

@xpivarc @akalenyu

[akalenyu]

Hey! How are you populating the PVC with a disk image?
If created through the DataVolume resource, CDI will orchestrate the overhead reservation

[silenceper]

@akalenyu Some empty data disks are not generated through DataVolume

[akalenyu]

@akalenyu Some empty data disks are not generated through DataVolume

Interesting, I see the name for this disk is "datavolumedisk1"

[silenceper]

@akalenyu It's just a name, because he is an ordinary pvc

[akalenyu]

@akalenyu It's just a name, because he is an ordinary pvc

Right so Filesystem overhead is a CDI feature and thus will not take effect without usage
of CDI. What's on this PVC? Have you considered creating a blank disk?
https://github.com/kubevirt/containerized-data-importer/blob/main/doc/datavolumes.md#blank-data-volume
Note you can also use populators to achieve the same without a DataVolume:
https://github.com/kubevirt/containerized-data-importer/blob/main/doc/cdi-populators.md