Running VMs with data images on external storage

[DennisLfromGA]

I've been interested in running VMs with data images on external storage and was following the crbug linked below and noticed that it is now 'fixed':

• Issue 827705 - Enable Running VMs with data images on external storage - chromium
  https://bugs.chromium.org/p/chromium/issues/detail?id=827705#c37

So I followed the instructions in the Crostini documentation linked below:

• ChromiumOS Docs - Running Custom Containers Under ChromeOS
  https://chromium.googlesource.com/chromiumos/docs/+/HEAD/containers_and_vms.md#how-can-i-run-vms-with-data-images-on-external-storage

I created a 4GB 'extra-disk.img' file successfully and then started the termina VM using it, also successfully I believe since there was a vmc process running with the '--extra-disk' argument.

I launched a Terminal session and started my penguin container, I can see the mountpoint for the extra-disk image but I cannot figure out a way to use it.

It doesn't appear among my 'Linux Shared folders' and I can't write to the /mnt/external/0 location with or without root permission.

So, I think there might be something I missed or it's not working as intended, possibly.

If anyone has had success with this I would be grateful if you could point out what I might be doing wrong or not doing.

We've been getting issues in the Chromebook forum from users having only a 16GB internal storage drive that would like to implement this feature but, so far, all attempts have been failing.

Thanx in advance,

~DennyL

[Keith I Myers]

Hello Denny,

I have gotten it to work but the instructions do need to be a bit more clear.

In crosh type

vmc enter termina

lxc config device add penguin extra_disk_0 disk source=/mnt/external/0 path=/home/username/directory

Replace username with your Lunix username and directory with the folder you wish to use. So in my case if I wanted to mount it to /home/kmyers/Workspace, I would use 

lxc config device add penguin extra_disk_0 disk source=/mnt/external/0 path=/home/kmyers/Workspace

I will warn you that your mileage will vary, it is not always consistent with remounting the disk and I have had cases where the disk will unmount randomly, often when my Chromebook goes to sleep. It is strongly recommended to keep things backed up if you try this.

-Keith

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[Denny Lockhart]

That worked Keith, thanx. 👍

It would be great if the Crostini docs be updated to include that crucial step.

Thanx again,

~DennyL

[DennisLfromGA]

Now I can't start the VM & container without first inserting the external media with the extra-disk.img file. :-(

This is just to much of a pain in its current state for me to fool with, plus I don't see how having an extra-disk image for storage is any better than inserting external media and 'Sharing it with Linux'. It very well could be that I don't fully understand how it's supposed to be used I guess.

~DennyL

[Keith I Myers]

The main advantage is that it supports file attributes. You cannot chmod +x a file that is "shared with Linux" but you can if mounted as a extra disk, this opens up the door for applications to be installed on external storage or software developers to use it as their workspace. 

[DennisLfromGA]

Well, those of us in Developer mode can remount the external media with the needed permissions, luckily.

Of course, that's not an option for the majority of Crostini users.

DennyL