@Bingbing Fang Thanks for reaching out.
When a VM applied artifacts, will the VM get artifacts from cache blob storage or from the real repository directly?
When DevTest Labs applies an artifact, it will read the artifact configuration and its files from the configured repositories. By default, DevTest Labs configures access to the public artifact repo. Depending on how a VM is configured, it may not have direct access to this repo. Therefore, by design, DevTest Labs caches the artifacts in a storage account that's created when the lab is first initialized.
What is the time frequency the cache artifacts will be synced? and how to sync on demand by force?
These caches will be re-created any time artifacts are applied. They'll be refreshed with the latest content from the respective referenced repositories.
Hope this helps. Do let us know if you have further questions.