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Bug#989462: About bumping Vagrant box disk image to 1TB

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Emmanuel Kasper:
> I did some testing around
> https://salsa.debian.org/cloud-team/debian-vagrant-images/-/tree/1TBv2
> (not merged in master yet) and I am still reluctant to merge the branch.
> I am OK to bump the default disk size to something like 40GB but not to 1TB.
> 
> The problem with the disk size of 1TB is as such: when you do a lot of
> write / erase cycles, the deletion of blocks is not propagated to the
> qcow2 backing disk image, so even though the OS in the VM reports only
> 2GB of block usage, the disk image could grow to 1TB, without the user
> knowing it.

Yeah, I also thought about that.  Would it be possible to ship the images with a 
disk/partition size of 1TB but keep a filesystem size of 20GB?  It is easy to 
expand the filesystem as needed.  The hard part is expanding the disk/partition 
size.

> I could reproduce this behavior running `fio` in the guest in a loop.
> I find this behavior dangerous.
> 
> At that point I see three possibilities:
> - you add to your pull request a change of the virtualized disk
> controller from virtio-blk to virtio-scsi and to the default libvirt
> vagrantfile the "unmap" option so that deletion of blocks in the guest
> are propagated om host storage

This sounds like the ideal solution.  I have no idea how much work it would be. 
  Do you?

> - you're fine with a disk image size of 40, or let's say 80GB

Chromium builds can take more than 100GB, so either of those would mean we still 
need to make our own basebox.

> - you use a shared folder for the builds. I just noticed vagrant-libvirt
> has also support for virtio-fs which according to its author has native
> host performance. If they are security concerns, let's discuss that in
> details and involve upstream if needed. virtio-fs is mature enough that
> it's use in production for Kata Containers in Kubernetes and OpenShift
> Sandboxed containers in the Red Hat Kubernetes offering.

We like the security isolation of throwing away all things that the build 
process has written to, so this option is less appealing, though perhaps 
workable.  It there was a host-controlled method of resetting the virtio-fs to a 
previous snapshot, then it could work.

.hc

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Thread

Bug#989462: About bumping Vagrant box disk image to 1TB Emmanuel Kasper <manu@debian.org> - 2022-01-20 19:30 +0100
  Bug#989462: About bumping Vagrant box disk image to 1TB Hans-Christoph Steiner <hans@eds.org> - 2022-01-21 12:20 +0100
    Bug#989462: Info received (About bumping Vagrant box disk image to 1TB) Hans-Christoph Steiner <hans@eds.org> - 2022-02-03 23:10 +0100
      Bug#989462: Info received (About bumping Vagrant box disk image to 1TB) Emmanuel Kasper <manu@debian.org> - 2022-02-05 14:10 +0100

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