Speeding up vagrant box add

Hello, I noticed today that while importing a newly created box file from packer into vagrant, vagrant seems to be copying the entire box file to a tmp file on the same disk, and then unpacking that box file. This template is ~20GB in size, so this takes quite a bit of time and also required that we have 40GB disk space available to store 2 copies of the box file, and then another 30GB for the extracted box. I am trying to optimize our packer build process and this seems like low hanging fruit.

Two questions come out of this:

  1. Is there any way to prevent vagrant from copying the box file before extracting it?
  2. This machine has an additional 10GB disk, which vagrant seems to be thick-provisioning on disk. Is there a way to have vagrant thin-provision the disk, which should again save us some time?

This was seen on vagrant 2.2.19 and 2.4.0 on Windows.


bump. Is this behavior by design?